Variable attaching to my page url?

I need a bit of help understanding this.

ive been having an issue with this url showing up in google searches:
http://www.weathersealhomeimprovements.net/index.html?wvsessionid=wv648c562e3292480ababd712b568f3fe9

i thought it may have been a cache problem with my hosting provider as they recently had a hardware failure and had to restore a backup of this domain.
so i contacted them and asked about it, but i dont quite follow what they are telling me.

here was their reply:

Hello,

This is generated by your index.html

When you include a variable at the end it just attaches it to the default page, for example when I manually type in index.html you get the same result.
http://www.weathersealhomeimprovements.net/index.html?wvsessionid=wv648c562e3292480ababd712b568f3fe9

?wvsessionid=wv648c562e3292480ababd712b568f3fe9 is not a page, it’s a variable that is being passed in the URL to the default page which in this instance is index.html

My question is, why is this variable being passed in the url when it never was before?
what could be generating this?

its a static html page with a bit of javascript. there’s no php or other dynamic content.

i feel extremely stupid, but i just dont understand what they are telling me here.

I’m familliar with PHP session ids, but I don’t know what “wv” means other than it’s the server adding the session id.

In case you don’t know what sessions are, they’re kind of like a server cookie that keeps track of a visitor across pages.

There might be a way to change the server settings to not do this, but you would need to know what your server is first before looking for more info.

Another thing we have found is a few of those social media integration tools will inject things in URLs. Typically fragments rather than query string variables, but it is pretty maddening . . .