Narrow grip or “real wide” grip pushups
These are real simple to do - pretty much like regular pushups, except the spacing between the arms varies. For the narrow grip pushups, move your hands closer towards each other - as close as you can comfortably get, while still maintaining the original pushup position. For me, I find a distance of between 8-10 inches works great on these pushups. You’ll find your triceps and inner chest working heavily on these movements.
For the wide grip pushups, extend your arms out REAL wide - beyond your shoulders, and do the pushups that way. Distance between the arms would probably be around 30 inches or so. This type of pushup is harder than it looks (to perform in correct form); so ease into the movement! These target the back muscles heavily, more than the narrow grip/regular pushups.