Acids are chemical compounds characterized by their ability to donate positively charged hydrogen ions (H+). They commonly dissolve in water, releasing these hydrogen ions, leading to the formation of hydronium ions. Acids range in strength from strong acids like hydrochloric acid and sulfuric acid to weak acids such as acetic acid found in vinegar. They are known for their sour taste and their ability to react with bases to form salts. Acids play a pivotal role in various applications, from industrial processes like chemical synthesis to everyday uses like food preservation and cleaning. They're also crucial in biological systems, involved in processes within the human body and other living organisms. The pH scale measures the acidity or basicity of a substance, with acids having a pH less than 7, indicating their acidic nature.