In The Elder Scrolls Online, players have the opportunity of wearing items sets. These sets give special bonuses to the player: some of them have a 3 items bonus and others have bonuses for 3 items and 5 items. Also, you can improve the set items quality like you would for any other items and enchant them with glyphs. Some of the set bonuses scale with the item level and quality while others are fixed.

How To Craft Item Sets
There are a few requirements for the craftable item sets, that you must meet in order to craft them (besides materials):

Traits:Each set has a number of traits you must have discovered for any item of the set you want to craft. The sets with the lowest requirements need only 2 traits researched, but they can go as high as 8 traits. For example, if you want to craft a helm from the Death’s Wind set, you need to have 2 traits discovered for helms (any 2 traits). This is a major incentive for players to research traits, since it’s a lengthy process, even for dedicated crafters.

Crafting Stations:Set items can’t be crafted at the regular crafting stations located in towns. There are special crafting stations for each of the craftable item sets (1 per faction). The Clothing station, Blacksmithing station and Woodworking station for each item set can be found at the same location. Crafting stations for 8 traits item sets are located in Coldharbour, The Earth Forge and Eyvea but cannot be reached unless you’ve progressed far enough through the main quest line, Fighter’s Guild quest line and Mages Guild quest line, respectively.