Two types of groups can be there in structure of carboxylic acid, one is electron withdrawing and other is electron donating. Electron donating groups decreases the acidity and Electron withdrawing groups increases the acidity of carboxylic acid, and also their nearness to carboxylic group creates more impact on acidity compared to the groups away from carboxylic group whether it is withdrawing or donating. For example, following is an acidity order: