Bribery and gift-giving is a well established occurrence in the world. Along with dialogue options, NPCs have the option of receiving gifts. For some, this means nothing. They will give you a quick thanks and be on their way. For others though, this will have an effect on gameplay. It will open up quests from some people, it will have others give you gifts in return, and some merchants may open up new inventory. There are some who you can begin romantic relationships with by way of gift-giving, though this is typically a long process. For your various allies, you can improve their performance of trade skills and combat. Bear in mind though that different people like different things. With twelve categories of gifts, you will have to listen to others to figure out what they want.