New to me - what are these unique identifier code?

[tylersprayman@gmail.com]

Just inherited a site from a client and it has these id codes after certain file names in the code. I have seen id's like these before but never had to deal with them until now. What are they, how are they generated, why do i need them, do they need to be changed? Also is css3366.css a specific typer of css file or is that simply what they named it?

Thanks

 

<link href="/theme/css/css3366.css?v=pldtNfMEx3LMrpYxMzy5kHd8Nj9-crskSwf8XfFY1L95M1" rel="stylesheet"/>

 

<script src="theme/modernizr6a4a?v=swfNR4I2pQwaJaYcnJKzgszzHI4XiJFBRh85GNOpQ1"></script>

 

<script src="theme/core7491?v=fbghb-nYUaHTaXmV7S2R3L9lBSsbR55ed4am7zYKTGM1"></script>

<script src="theme/val0afa?v=vmrtfkiL2Z90AUp5Gi6ez5WZrJN9rUNzMngdnJaAqtD16g1"></script>

<script src="theme/custom90f8?v=kvtydeDI85AzbxW9vscIznBXvh1RAI8xRtta9VsEFIOzs1"></script>

[Ingolme]

I would say it's just there to prevent browsers from using the cached version of the file after a change has been made to the CSS or Javascript, I suspect it's probably a hash of the file contents. It's not required for the file to load.

 

css3366.css is the name of the file. To me it looks like these files and the HTML were generated by a content management system.

[dsonesuk]

Cached file are updated to specific time period or when file is changed, these are uniquely identified so the new css will overide old when encounted, also these files would be minimised prior to being cached.