What does %5B and %5D in POST requests stand for?

The strings "%5B" and "%5D" are URL-encoded versions of the square brackets "[" and "]", respectively. In a POST request, these characters are often used to enclose the name and value of a form field.

For example, consider the following POST request:

POST /somepage HTTP/1.1
Content-Type: application/x-www-form-urlencoded


In this example, the POST request has three fields: "field1", "field2", and "field[3]". The third field has a URL-encoded name of "field%5B3%5D", which is equivalent to "field[3]".

URL encoding is a way to encode special characters in a URL so that they can be transmitted over the internet. The characters "%5B" and "%5D" are the URL-encoded versions of "[" and "]", respectively. Other common URL-encoded characters include "%20" (a space), "%3A" (a colon), and "%2F" (a forward slash).

I hope this helps! Let me know if you have any further questions.