What is TikTok? Definition, history and how it works

How does TikTok work?

TikTok works by ranking every video for every user individually in the For You feed, instead of showing posts mainly from accounts you follow. Users record or upload clips from 3 seconds up to 60 minutes long, add sounds, captions and hashtags, and the app distributes them to a test audience first. Videos that keep people watching get shown to more users, which is why a new account with zero followers can still go viral.

In a June 2020 newsroom post, TikTok named three groups of ranking signals:

• User interactions: likes, shares, follows, comments and the videos you create.
• Video information: captions, sounds and hashtags.
• Device and account settings: language, country and device type, which TikTok says carry lower weight.

History of TikTok: key dates

TikTok grew from a Chinese app called Douyin and a merger with Musical.ly. The table lists the milestones.

In the US joint venture, Oracle, Silver Lake and MGX hold 15% each. Shou Zi Chew has been TikTok’s CEO since May 2021, and the company operates from Singapore and Los Angeles.

TikTok users in numbers

TikTok reaches about one in five people on Earth with its ads. DataReportal’s January 2025 data shows an ad reach equal to 19.4% of the world’s population, with men making up 55.7% of that audience. The largest markets are the United States (136 million), Indonesia (108 million) and Brazil (91.7 million). In Poland, DataReportal’s Digital 2026 report counts 12.4 million adult users reachable with TikTok ads, which is 39.8% of Poles aged 18 and over.

TikTok in marketing, SEO and AI search

TikTok matters to marketers because people now use it to search, not only to scroll. In July 2022, Google’s Prabhakar Raghavan said that almost 40% of 18 to 24-year-olds in an internal US survey went to TikTok or Instagram instead of Google Maps or Search when looking for a place to eat. That makes TikTok a real search engine competitor for product and local queries.

TikTok SEO

TikTok SEO means optimising videos for in-app search: spoken keywords, on-screen text, captions and hashtags all feed the index. In my SEO projects I treat a TikTok keyword list exactly like a Google keyword list, built per country and per language, because a phrase that works in Poland rarely matches the phrase used in Germany.

TikTok ads and creators

TikTok Ads Manager sells In-Feed ads, Spark Ads (boosted creator posts) and TopView placements. Creator partnerships work well for buzz marketing, while short vertical edits can be reused as Instagram Reels.

TikTok and generative search

Google indexes public TikTok videos, and AI answer engines cite them for “how to” and product questions. Brands that publish clear, captioned videos give these systems quotable content, which supports Generative Engine Optimization. I cover this in more detail on the AI SEO services page.

TikTok vs Instagram Reels

For brands entering several countries, TikTok content should follow the same market logic as the website. Read how I plan this in international SEO projects.