A tag is a keyword or label that categorizes your question with other, similar questions. Using the right tags makes it easier for others to find and answer your question.
a lightweight, plain-text, markup language. It is used across the entire Stack Exchange network for post formatting (Questions, answers, wikis, chat) and comment formatting.
For *either* meta questions about Stack Apps, or about how per-site metas are exposed by the API. (Stack Apps is its own meta site)
For BUG REPORTS, not feature-requests. Use this when the API doesn't return data when the docs (or similar calls) say it should. This tag may be eliminated in the future.
its own meta site. Use this tag to help differentiate moderation questions from the usual Stack Apps post.
Questions about Stack Exchange notifications and the API routes that provide them. Not about apps that provide notifications - use [notifier] instead.
Apps that provide notifications of things happening.
an open standard for authorization.
For questions relating to version 2 of OAuth, which is an open standard for authorization. See also the tag oauth.
Apps, Scripts, Libraries, Bugs, Feature-requests, or APIs that are: deprecated, no longer available/supported, or no longer relevant.
For questions related to the use of paging (returning a limited number of results, and using a page parameter to get the next batch) in the Stack Exchange API.
a high-level, general-purpose, interpreted, dynamic programming language.
Questions about using PHP code to interact with Stack Exchange and/or the Stack Exchange API. ... For general PHP questions, post on Stack Overflow instead.
For apps that don't quite work yet, but need a registered Stack Apps post for testing. If you're following a tutorial which asks to post a placeholder app here, that's fine, but please delete it after…
"Posts" covers both questions and answers. (And perhaps wiki pages) For example, you may use this tag for apps that help with general editing.
Accompanies [app]s written in, or [library]s meant to be used from, the Python programming language
Tools that help with questions, or issues with the API handling of questions.
For questions about the maximum number of API calls per day, AKA 'quota'; 300 for unregistered apps, and 10000 for registered apps (per user when using personalized access tokens, per app otherwise).
Questions about: throttling, the `backoff` flag, the quotas, or the rate limiting of requests made to the API. API calls are restricted both by per-second rates and by daily quotas.
Questions about displaying things with minimal latency, or apps that do so.
User reputation as returned by the API or displayed on Stack Exchange sites