Cover

Cover provides a degree of protection to a target behind it. There are three degrees of cover, each of which provides a different benefit to a target: Half Cover (+2 bonus to AC and Dexterity saving throws), Three-Quarters Cover (+5 bonus to AC and Dexterity saving throws), and Total Cover (can't be targeted directly). If behind more than one degree of cover, a target benefits only from the most protective degree. See also chapter 1 ("Combat").