The "Filter" button. Does it do anything?

When I hover over a tag, I see two buttons, “Watch” and “Filter”. When I click “Watch”, I see all content tagged with that in my “browse watched images” bit. I have been assuming that likewise after I click “Filter”, I never see images tagged with that tag. But is this actually true? I’ve just seen an image that I definitely filtered. Does something else have to happen?

Your currently selected filter is “Everything”. That means nothing is being filtered.
 
Select the filter that you want to use, and make sure that spoilers are set to “static” (the pull-down menu to the right of the filters menu).
 
After doing that, if the things you want to have filtered are not being filtered, or if you are not able to select a filter, please send me a PM and I will help you.

@PoemeMystique  
I believe the reason is because you’re currently using the Site’s filters. Those are set and can’t be edited by people.
 
For your own filter, go Here and look under “My Filters” for a tip on how to set yours up. When using your own filter you’ll be able to add tags to it by mousing over them.
 
Edit: Accursed Derpy Ninjas!

Thank you. So I can’t just filter things as and when I see them by clicking “Filter”? Or will I be able to do that once I’ve selected a filter from the options available?

@PoemeMystique  
If you’re using a custom filter, you can. You should have an option to create a copy of Everything and just add to there via tags.

Okay, thanks everyone. I think it’s working the way I want it now.