Applies a Name and/or a series of tags to an object and allows to pick those object by Name or Tag. This behavior is thought to resemble the HTML/CSS idea of ids and classes, where you can pick an individual element by Id, but multiple elements by one of its multiple classes.
In our case, the Name is sort of an Id you can give to an object, so, the ideal is to give each object a unique one (though, it's not mandatory).
And the Tags are a series of classes many objects may belong to. Use this property to group objects by a certain characteristic. Any single object can have many tags and there are events for the addition or removal of tags, allowing to do lots of changes to an object as soon as a tag is added/removed, just like HTML when you add/remove a class from an element.