A linkshell is a group of people that have an item that allow them to talk together across the game world regardless of location. Depending on what they plan to do it can be a group of people wanting to gather for doing end games stuff like beating monsters that require a lot of people and teamwork from people you're familiar with. In our case we'll be mostly using it for socializing and helping each other out since you'll be able to quickly talk to someone and call them for help.