The pH scale at 25 C spans from 0 to 14. From 0 -7 are the acids and 7-14 are called bases. pH= 7 is called as the neutral and pure water is the best example for a neutral solution.
Strong acids have pH value close to 0 and examples for strong acids are concentrated sulfuric acid, concentrated HCl. Weak acids have pH close to 7, usually in the range of 5-7. Some typical examples are citric acid and acetic acid.
Weak bases have pH values slightly higher than 7. Examples for weak bases are Na2CO3. Strong bases have pH close to 14 but often over 12. Some typical examples are NaOH, KOH and LiOH.
A strong acid would neutralize with a strong base to form a neutral solution(pH=7) while with a weak base it would result in an acidic solution (pH <7). A strong base would react with a weak acid to form an alkaline (basic) solution (pH >7) and with weak acid it would form a solution which is almost neutral.
Both acid and base solutions form electrolytic solutions which conduct electricity.
In Litmus test, acids change litmus paper red while bases change it to blue. Acids usually react with metals and bases usually reacts with non metals.