The Stack Exchange API is based on HTTP and URLs, just like the web page you're browsing now. Except instead of HTML, the responses are all in JSON.
Let's say we wanted to call the /info method:
All API methods can be found at https://api.stackexchange.com/docs.
Global Method Parameters
All methods accept the following parameters:
type=jsontext: responds with mime-type text/json.
If you've created an application, script, or library for use on the Stack Exchange network, that's fantastic!
Now publicize it by creating a question with the correct tag:
The /sites method is used to enumerate all sites in the network. If your [app] is meant to run against more than a single site (and many are) this method is how you should be discovering new sites in ...
What are the API request limits?
A single IP address can only make a certain number of API requests per day, depending on the presence of a valid API key.
Default API daily limits: