A rate limit caps how many requests a client may send to an API in a given time window, for example 200 calls per hour. Send more and the API rejects the extra requests, usually with HTTP status 429, "too many requests", until the window resets.
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Why APIs enforce rate limits
Limits protect the service from being overwhelmed and keep one heavy user from degrading everyone else. Social platforms are especially strict: publishing endpoints often have per-account quotas on top of general request limits, because mass automated posting is exactly what spam looks like.
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How to handle hitting a limit
A 429 is not an error to panic about; it is an instruction to slow down. Well-behaved clients wait and retry with increasing delays (called backoff) and read the response headers that say when the window resets. When you build on a publishing API, check your quota before you need it: InvisibleAPI exposes live usage limits through the API, with a quota of 100 published posts per connected account per billing period.
Go from the definition to the docs that show how to apply it.
Primary solution Account rules and constraints