Extended Thinking
Also: extended thinking mode, Claude thinking mode
Extended thinking is a mode where Claude works through a problem step-by-step before giving its final answer. You see its reasoning process — including the parts where it changes its mind or catches an error. It takes longer and costs more tokens, but produces meaningfully better results on hard problems: complex analysis, multi-step planning, tricky reasoning tasks. Turn it on when accuracy matters more than speed.
In practice
You ask Claude "should we expand into the EU market this year?" With Extended Thinking on, Claude works through the question visibly — considering regulatory complexity, market size, team bandwidth, timing — before giving its recommendation. You can see where it weighed tradeoffs. Use it for decisions that deserve actual analysis, not quick answers.
Related concepts
Where Extended Thinking shows up
2 articlesExtended Thinking gives Claude time to reason through hard problems before answering. Here is what it is actually good for, and what it adds over standard Claude.
Extended thinking makes Claude noticeably better on hard problems. But most tasks don't need it, and using it everywhere will slow you down and cost more.