An interesting aspect of the Neopets site, Guilds are a popular activity, even though the success and importance of most of them is often questioned. By joining or creating a guild, you can interact with Neopets users from all over the world who have interests similar to yours. For instance, all sorts of guilds exist in Neopia, ranging from Grey Faerie Followers to Help Site Guilds, and from the Battledome Elite to Fans of Harry Potter. Practically everything has at least one guild dedicated to it, and if it doesn't, you can always create one of your own.
Guilds are without question a controversial feature on Neopets because some people have been known to start guilds and take advantage of new or naive users. For instance, a Guild Master may befriend a lot of users, and then request that each one pay a monthly fee of One Codestone for membership. Or, they might run a contest which also requires an entrance fee, but once the fee is paid, the Guild Master disappears with the profits.
Fortunately, reasonably amount guilds are far from evil. These guilds have lots of fun activities, are frequently updated, and are a great way for users to make new friends. Just make sure that, if you're going to join a guild, you check up on its reputation.