That error means that **you have used up your API quota for the day.**

You are allowed either 300 or 10,000 API requests per day for each IP address, or app, depending on whether you use an application `key` and/or an `access_token`.  

See:

 1. [The "Throttles" documentation][1]
 2. [What are the API request limits? (FAQ)][2]
 3. [Request Throttling Limits (FAQ)][3]

Note that [you must pass the `key` with every call to get the quota benefit][4].


  [1]: https://api.stackexchange.com/docs/throttle
  [2]: https://stackapps.com/questions/67/how-api-keys-work
  [3]: https://stackapps.com/questions/1143/request-throttling-limits
  [4]: https://stackapps.com/a/6962/7653