Introduction to the meaning of parameters behind js css_Basic knowledge

Browsing some websites, I often see that there are always some parameters behind the js css of web links. I checked it in detail today:

There are two main possibilities for this situation:

Script It does not exist, but is dynamically generated on the server side, with a parameter indicating the version number of the generated script file.

In order to speed up the response, some clients will cache the corresponding js css. Therefore, every time you upgrade the js css version number and change the corresponding version number, the client browser will automatically update the new version. js or css

The second case should be the most common