Answer:
An acid is a compound that donates hydrogen ions to a solution
Explanation:
This is the Bronsted-Lory theory where the acids are compounds which donates H+ to others while basis are compounds that donates OH-.
HCl  +  H2O →  Cl-  +  H3O+
In Lewis's theory, acids accept e- while basis donates them.
In Arrhenius theory, acids are the compounds that has H in its formula while basis has OH
