AI search has changed so fast since 2023 that a product, a model, an ad policy or a publisher control described last year may already be out of date. This page is a dated timeline of AI answer engines from Microsoft's new Bing preview in February 2023 to November 2026: launches, general rollouts, model changes, browser products, a deprecation, an API retirement, the arrival of ads and new publisher controls. Every date comes from the provider's own announcement or documentation page. It is written for publishers, marketers, privacy and security teams, and anyone who needs to know when something happened rather than opinions about it. Engines are listed alphabetically where they appear side by side, and the order is never a ranking.
Last checked: 2026-11-15.
This is an independent reference page from NHI Mgmt Group based on public provider documentation; it is not sponsored or endorsed by any provider.
Key takeaways
- 2023 started the race. Microsoft opened a limited desktop preview of the new AI-powered Bing on 7 February 2023, and Google introduced the Search Generative Experience in Search Labs on 10 May 2023.
- 2024 and 2025 brought AI answers to everyone. Google began rolling out AI Overviews to everyone in the US on 14 May 2024, and OpenAI opened ChatGPT search to everyone where ChatGPT is available, with no sign-up, on 5 February 2025.
- Browsers became answer engines. Perplexity launched Comet on 9 July 2025 and OpenAI launched ChatGPT Atlas on 21 October 2025; OpenAI's Atlas page now says Atlas "has since been deprecated".
- 2026 is the year of ads and merges. OpenAI set out its ads test for ChatGPT Free and Go on 16 January 2026, Google merged AI Overviews and AI Mode into one AI Search experience on 20 May 2026, and Google scaled AI Mode ads to ten more markets on 28 October 2026.
- Publisher controls are being rewritten. Microsoft announced separate AI training and AI grounding preferences for Bing on 30 October 2026, with dates running from 15 December 2026 to 30 September 2027.
Master timeline
As of 15 November 2026. Dates are the publication dates of the provider's own announcement unless the event row says otherwise. Where a provider gives only a month, season or quarter, that is all the table shows.
| Date | Provider and product | Event type | Event |
|---|---|---|---|
| 7 February 2023 | Microsoft Bing | Launch (preview) | New AI-powered Bing and Edge, described as a "copilot for the web", in limited preview on desktop, running a next-generation OpenAI model customised for search with Microsoft's Prometheus model |
| 10 May 2023 | Google Search | Experiment | Search Generative Experience (SGE) introduced in Search Labs, US and English only, on Chrome desktop and the Google app |
| 14 May 2024 | Google AI Overviews | General rollout | AI Overviews begin rolling out to everyone in the US, with Google expecting to reach over a billion people by the end of 2024 |
| 25 July 2024 | OpenAI SearchGPT | Prototype | SearchGPT prototype announced (date as shown in OpenAI's related link on the ChatGPT search post) |
| 31 October 2024 | OpenAI ChatGPT search | Launch | ChatGPT search for Plus and Team users and SearchGPT waitlist users, with Enterprise, Edu and Free users to follow |
| 16 December 2024 | OpenAI ChatGPT search | Expansion | Opened to all logged-in users where ChatGPT is available |
| 5 February 2025 | OpenAI ChatGPT search | Expansion | Available to everyone where ChatGPT is available, with no sign-up required |
| 5 March 2025 | Google AI Mode | Experiment | AI Mode introduced as an opt-in Labs experiment, Google One AI Premium subscribers first, on a custom Gemini 2.0 |
| 5 March 2025 | Google AI Overviews | Model and access change | Gemini 2.0 used for harder US queries; teens can use AI Overviews; sign-in no longer needed |
| 15 May 2025 | Microsoft Bing Search APIs | Retirement notice | Lifecycle page published (page metadata date) announcing retirement of Bing Search APIs on 11 August 2025 |
| 20 May 2025 | Google AI Mode | General rollout | AI Mode rolls out in the US with no Labs sign-up; a custom Gemini 2.5 comes to AI Mode and AI Overviews in the US |
| 9 July 2025 | Perplexity Comet | Launch | Comet browser with an AI assistant, first for Perplexity Max subscribers, then invite-only from a waitlist |
| 11 August 2025 | Microsoft Bing Search APIs | Retirement | Bing Search APIs retired; Microsoft names Grounding with Bing Search in Azure AI Agents as the replacement |
| 3 September 2025 | You.com | Funding | $100 million Series C at a $1.5 billion valuation, led by Cox Enterprises; You.com reports over 1 billion API queries a month (provider figure) |
| 21 October 2025 | OpenAI ChatGPT Atlas | Launch | Atlas browser with ChatGPT built in, on macOS, with agent mode in preview for Plus, Pro and Business |
| 16 January 2026 | OpenAI ChatGPT | Ads policy | OpenAI sets out its plan to test ads for Free and Go users, logged-in adults in the US; Plus, Pro, Business and Enterprise without ads |
| 27 January 2026 | Yahoo Scout | Launch (beta) | AI answer engine in beta for US users, with Claude as primary model and Bing's grounding API |
| 20 May 2026 | Google AI Search | Merge and model change | AI Overviews and AI Mode merged into one AI Search experience worldwide; Gemini 3.5 Flash becomes the AI Mode default |
| 5 August 2026 | You.com Answer API | Launch | Single-call answer API with citations |
| 26 October 2026 | You.com Inference Router | Launch | OpenAI-compatible and Anthropic-compatible endpoints with built-in web tools (changelog date; the launch blog post is dated 22 October 2026) |
| 28 October 2026 | Google AI Mode | Ads expansion | Ads scale in ten markets; multiturn ads launch in the US; Brazil, Mexico and the UK planned for Q4 2026 |
| 30 October 2026 | Microsoft Bing | Publisher controls | AI Training and AI Grounding preferences announced, replacing NoArchive and NoCache for these purposes |
Engine-by-engine history
Each engine below gets the same fields: first AI search event, wider rollout, model changes named by the provider, and the latest dated change. Engines are listed alphabetically.
Google AI Overviews and AI Mode
- First event: SGE in Search Labs on 10 May 2023, offering an AI-generated overview with links and a conversational follow-up mode.
- Wider rollout: AI Overviews to everyone in the US from 14 May 2024; AI Mode as a Labs experiment on 5 March 2025 and to the US without sign-up on 20 May 2025.
- Models named: a custom Gemini model for Search (May 2024), Gemini 2.0 for harder AI Overviews queries and a custom Gemini 2.0 for AI Mode (March 2025), a custom Gemini 2.5 for both in the US (May 2025), Gemini 3.5 Flash as AI Mode default (May 2026).
- Latest dated change: AI Mode ads scaling in ten more markets with multiturn ads in the US (28 October 2026). Google reported that AI Mode passed 1 billion monthly users (provider figure, May 2026).
The full product history is in Google AI Mode Explained and Google AI Overviews Explained.
Microsoft Bing and Copilot
- First event: new AI-powered Bing and Edge in limited desktop preview on 7 February 2023, with links to the web content it references.
- Wider rollout: the February 2023 post planned expansion to millions of users within weeks and a mobile preview later.
- Models named: a next-generation OpenAI large language model customised for search, working with Microsoft's Prometheus model.
- Latest dated change: AI Training and AI Grounding preferences announced on 30 October 2026. Developer access changed earlier: Bing Search APIs were retired on 11 August 2025.
The consumer product today is covered in Microsoft Copilot Web Answers Explained.
OpenAI ChatGPT search and Atlas
- First event: SearchGPT prototype on 25 July 2024.
- Wider rollout: ChatGPT search launched on 31 October 2024, opened to all logged-in users on 16 December 2024 and to everyone without sign-up on 5 February 2025.
- Models named: a fine-tuned version of GPT-4o, post-trained with synthetic data including outputs distilled from o1-preview (October 2024 post).
- Latest dated change: the ads test plan for Free and Go users in the US (16 January 2026). Atlas launched on 21 October 2025 and OpenAI's Atlas page now states it "has since been deprecated", without a date.
Perplexity
- First event on this page: Comet launched on 9 July 2025.
- Wider rollout: Comet went first to Max subscribers, then by invitation from a waitlist over the summer of 2025.
- Models named: the Comet launch post describes an assistant that answers questions and carries out multi-step browsing tasks; model names for the answer engine are on the product profile.
- Latest dated change: plan and Comet query limits are covered on the profile page.
See Perplexity AI Explained and, for browser risk, the Agentic Browsers Security Guide.
You.com
- First event: You.com's Series C post says that in December 2022, after ChatGPT launched, it began connecting large language models to live web data with citations.
- Wider rollout: customer requests led to its APIs and a shift towards AI infrastructure, per the same post.
- Models named: the Inference Router lists open-weight models behind one API (October 2026).
- Latest dated change: Inference Router launch (26 October 2026 in the changelog).
See You.com Explained.
Yahoo Scout
- First event: beta launch for US users on 27 January 2026.
- Wider rollout: available on Scout.Yahoo.com and in the Yahoo Search app for iOS and Android, rolling out across Yahoo's portfolio.
- Models named: Claude from Anthropic as primary foundational model.
- Latest dated change: the January 2026 launch is the latest dated event on Yahoo's press page used here.
Shutdowns, deprecations and retirements
| Product | Provider | Announced | Effective | Stated successor or replacement |
|---|---|---|---|---|
| Bing Search APIs | Microsoft | Lifecycle page published 15 May 2025 (metadata) | 11 August 2025; existing instances decommissioned and no new sign-ups | Grounding with Bing Search as part of Azure AI Agents |
| ChatGPT Atlas | OpenAI | Not dated on the Atlas launch page | The page states Atlas "has since been deprecated" | The page directs readers to current product resources |
| SGE as a Labs experiment | 14 May 2024 | AI Overviews grew out of the Search Labs experiment and began rolling out to everyone in the US | AI Overviews, later merged with AI Mode (20 May 2026) |
As of 15 November 2026. Retirements matter beyond the product itself: the Bing Search APIs retirement forced developers who used Bing results to ground their own applications to move to another search API or to Microsoft's agent grounding tool, and You.com published a migration post on 12 August 2025, the day after the retirement.
Ads in AI answers
| Date | Provider | Change | Plans or markets stated | Label or principle stated |
|---|---|---|---|---|
| 16 January 2026 | OpenAI | Plan to test ads in ChatGPT | Free and Go, logged-in adults in the US; no ads on Plus, Pro, Business or Enterprise | Ads separate from answers and marked as sponsored; OpenAI says ads do not influence answers; no ads for users identified or predicted to be under 18 or near sensitive topics such as health, mental health and politics |
| 28 October 2026 | AI Mode ads scaled to ten markets; multiturn ads in the US | Australia, Canada, India, Kenya, Malaysia, New Zealand, Nigeria, Pakistan, the Philippines, Singapore; Brazil, Mexico and the UK planned for Q4 2026 | Labelled "Sponsored" |
As of 15 November 2026. Market-by-market detail across engines is kept in the Ads in AI Answers Tracker.
Publisher control changes
The controls publishers use to allow or limit AI use of their pages have their own timeline. The Bing change is the most date-heavy so far.
| Date | Provider | What happens |
|---|---|---|
| 30 October 2026 | Microsoft | AI Training preference (robots.txt user agent __usage_ai-training, or a Bingbot meta tag or X-Robots-Tag) and page-level AI Grounding preference with values Allow (default), DisallowExtended and Disallow announced |
| 15 December 2026 | Microsoft | Temporary grounding transition preferences open in Bing Webmaster Tools, only for sites using NoArchive or NoCache on that date |
| 1 February 2027 | Microsoft | Microsoft starts honouring the new preferences as it crawls; where found, remaining NoArchive and NoCache tags are ignored on that site |
| 1 March 2027 | Microsoft | NoArchive and NoCache no longer read as training or grounding preferences; pages without a temporary grounding preference default to Allow until recrawled |
| 30 September 2027 | Microsoft | Temporary grounding preferences expire, or earlier if a recrawl finds the new page-level preference |
As of 15 November 2026. Google, OpenAI and Perplexity controls, with user-agent names, are compared in the AI Crawler and Grounding Controls Tracker; the wider practice is in AI Crawler and Scraper Controls.
Patterns across the timeline
- Experiment, then default: Google moved from a Labs experiment (May 2023) to US rollout (May 2024) to a merged worldwide experience (May 2026). OpenAI went from prototype (July 2024) to no-sign-up access (February 2025). Gaps of roughly 6 to 12 months between preview and general access recur.
- Model swaps without a product change: Google named five model changes for AI Overviews and AI Mode between May 2024 and May 2026. Answers to the same question can change when the model changes, even where the interface does not.
- Grounding sources are shared: Yahoo Scout uses Bing's grounding API, ChatGPT search uses unnamed third-party search providers plus partner content, and You.com sells search results to other products. One index change can ripple into several engines.
- Browsers are the newest and least stable layer: two AI browsers launched in 2025, and one is now described by its provider as deprecated.
- Monetisation arrived in 2026: both ad programmes on this page are dated 2026 and both are rolling out by market and plan.
What these events mean for teams
| Event type | Who should act | What to review |
|---|---|---|
| Launch or rollout to free users | Security, IT, data protection | Whether staff may use the engine for work, which account type, and what data may be entered; see the Safe Use of AI Chatbots Guide |
| Model change | Content owners, risk teams | Re-test how key questions about your organisation are answered |
| Ads introduced | Marketing, brand, compliance | Placement, labelling and how sponsored content appears next to answers about your brand |
| Publisher control change | Web and SEO teams, legal | robots.txt, meta tags and headers before the stated effective dates |
| Deprecation or API retirement | Engineering, procurement | Integrations, API keys and contracts tied to the retiring product, and the stated replacement |
Answer manipulation is a separate risk with its own history: see LLM Grooming and AI Search Poisoning.
How dates on this page are defined
- Announcement date: the date printed on the provider's blog post, press release or documentation page.
- Effective date: used only where the provider states one, as in the Bing Search APIs retirement and the Bing publisher control dates.
- Metadata date: where a page prints no announcement date, the page's publish metadata is shown and labelled as such.
- Provider figures: usage numbers such as "over 1 billion monthly users" are the provider's own claims and are labelled that way.
- Different dates for one event: where a blog and a changelog differ, both are given.
- Left out: events that could not be confirmed on an official page, including undated reports of shutdowns and country counts carried only by press coverage.
Practitioner checklist
- Keep an internal register of the AI search engines staff use, with the launch and plan facts from this page and the account type approved for work.
- Put 1 February 2027 and 1 March 2027 in the web team calendar and publish Bing AI Training and AI Grounding preferences before then if you rely on NoArchive or NoCache.
- After any model change named by a provider, re-run a fixed set of questions about your organisation and record the answers and cited sources.
- Check whether any internal tool still depends on a retired product, such as Bing Search APIs, and confirm the replacement and its API keys are inventoried.
- If you advertise in a listed market, review how ads in AI answers are labelled and placed next to answers about your brand.
- Remove or block deprecated AI browsers from managed endpoints and review the data they held.
- Re-check dates against the provider's page before using them in a decision; this field changes monthly.
Standards and references
- Google: Supercharging Search with generative AI (SGE)
- Google: Generative AI in Search, May 2024
- Google: I/O 2026 announcements
- Microsoft: Reinventing search with a new AI-powered Bing and Edge
- Microsoft Learn: Bing Search API retirement
- Microsoft Bing: Clearer preferences for training and grounding
- OpenAI: Introducing ChatGPT search
- OpenAI: Our approach to advertising and expanding access
Further dated sources used: Google: AI Mode (March 2025), Google: AI Mode update (May 2025), Google: Ads in AI Mode expansion, OpenAI: Introducing ChatGPT Atlas, Perplexity: Introducing Comet, Yahoo: Introducing Yahoo Scout, You.com: Series C and You.com: API changelog.
Related NHI Mgmt Group resources: AI Answer Engines Hub · AI Search Engines Compared · Ads in AI Answers Tracker · AI Crawler and Grounding Controls Tracker