What types of substances accept protons in certain reactions?

Answer 1

A compound that donates a proton to solution (or another compound) is a Bronsted-Lowry acid, while a compound that accepts a proton from solution (or another compound) is a Bronsted-Lowry base.

Therefore, acid-base chemistry is concerned with the transfer of protons from one species to another.

In this way, an acid-base reaction is the transfer of a proton from a proton donor (BL acid) to a proton acceptor (BL base).

Cheers!

Answer 2

The definition of a base is a proton ACCEPTOR or receiver. The proton DONOR or the species that gives away it's proton (Which is the H+ or Hydrogen component) is the acid.

So essentially BASES accept protons, while acids give them away.