system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If there's actually an advantage to using foam, solid or liquid soap over the other 2

I've heard people talk about how one is better than the other but never really specify why.

There may be nothing better, but if there is which is the most advantageous to use and why?
gpt
A recent study has suggested that solid soap can retain germs on its surface. You can dislodge a lot of them by simply rinsing it off, but it does provide a minor benefit in that a dispenser type soap can help sidestep that problem. However, if reusing the bottle one needs to clean it thoroughly or else you're potentially just in the same boat, getting germs inside of it. 

So a bar of soap may be less desirable in a social setting like a public restroom, where it can pass through many hands and not be subjected to the tightest level of cleanliness.