There are various Upgrades that can be applied to Geralt, as well as his weapons and armor, in The Witcher 3: Wild Hunt.

In your travels, Geralt will gain ability points (both by leveling up, and discovering Places of Power for the first time). You will be able to spend these ability points on Character Abilities, which can be customized and improved to customize your ideal Witcher.

There are also several types of Gear Upgrades that can be either bought from merchants, or found in special chests that will let you upgrade and modify your skill set. These can be applied to any gear with a socket, and can also be removed.

As you traverse the wide open lands of the Northern Kingdoms, Geralt will also be able to find or purchase upgrades for his horse, Roach. These Horse Upgrades can change the amount you can carry, let your horse run faster, and more.

Finally, after defeating some of the more fearsome monsters of the land, you will be able to carry the Monster Trophies of creatures you have slain for a Witcher Contract. Equipping one to your saddle will grant Geralt different passive enhancements that can work well alongside particular abilities.