Protic solvents have the ability to form hydrogen bonds to the nucleophile. They are polar in nature. They have a hydrogen directly bonded to nitrogen or oxygen. They are especially favourable for $S_{N^{1}}$ reactions. while aprotic solvents can’t have hydrogen bond to the nucleophile because they donot have hydrogen bonded to nitrogen or oxygen. They are favourable for $S_{N} 2$ reactions
$H_{2}O, ROH, R— COOH$ etc are protic solvents because they are polar in nature and contain a hydrogen directly bonded to oxygen while other are aprotic solvents as they do not have a
hydrogen bonded directly to the oxygen