A handgun holster should secure your firearm while keeping it readily accessible in case of an emergency. A good holster will shield the trigger from accidental interactions and be easy to draw from in a streamlined, fluid motion.
Holsters can be inside the waistband (IWB) or outside the waistband (OWB). Popular for concealed carry, IWB holsters typically loop or clip to your belt, and trade a bit of discomfort and exposure of the handgun to sweat for increased concealment. OWB holsters typically have wide wings to smooth out the firearm’s shape under a shirt, and are a better option for a larger handgun. You can also find shoulder holsters (a comfortable option, especially for larger revolvers), pocket holsters (preventing snags for a small handgun in your pant or coat pocket), ankle holsters (often used for backup guns, as they offer great concealment but more difficult draws), belly band holsters (a less comfortable option providing greater concealment).
Holsters are typically made from leather, kydex, or synthetic fabric. Leather is the traditional choice, and offers a versatile option that requires some maintenance. Kydex is a tough plastic that can mold around your gun, but can be less comfortable. Sythentic fabrics can be more bulky but also more comfortable than kydex.
When choosing a holster, find an option that works for your comfort, gun size, and wardrobe.