What is acid & base?

Question

please explain it

Answer 1

An acid is an ionic compound that forms H+ ions when dissolved in water.  A base is an ionic compound that forms OH- when dissloved in water.   If you mix an acid and a base, the H+ and the OH- combined to form water.  That is the basic way to discribe it.  

Answer 2

I just want to add to Paul's answer.

One way to indicate the difference between acid's and base's (or caustic's) is through the use of a pH meter. The meter has a scale numbered 1 to 14 with acid's toward 1 and base's toward 14. The middle value of 7 is a non-corrosive measure like drinking water.