What does this line of code mean?

[carllucas]

Can anyone explain this line of code to me:

<script type="text/javascript" id="StartupScript" src="StartupScript.js?v=1" >

For example why is it necessary to create an id for the script? And what does the ?v=1 mean after the script name

Thanks much

[iam_clint]

the ?v=1 is a variable transferred to the javascript the same way the get method in a form works.
giving it an id just gives the line something to identify it by.