Acid means the substance which release H+ ions when dissolved in aqueous solutionĀ is called as acid
acids are basically sour in taste.
acids are classified on the basis whether their ph level is less than 7 or notĀ 
prop of acid:
acid +metal oxide--------------->salt + water
acid +metal hydrogen carbonate--------------->salt + water+co2
acid+metal------------------------>salt +hydrogen gas
acids are good conductors of heat and electricity so used as electrolytes