Checkbox in Cart?

[KES99]

I'm trying to find answers to questions that I'm pretty sure have been asked before. One such thing now is:

What is the checkbox shown in the cart for. it has no description against it and whatever i do with it it seems to have no action attached to it.

Now I've searched in many variations such as:

shopping cart checkbox
cart checkbox
what is cart checkbox

etc etc

but each time I come up with litterally dozens of pages each with dozens of post. Who has the time to wade through all of those? I'm reluctant to post here asking for the answer to my question as I'm sure it has already been asked...But where...how can I get better search results????????????