Data and Objects In this section, we are going to consider the important topics of objects and collections. Objects can be thought of as collections of properties. Properties can be designated for an object and additional properties can be added on the fly. If you attempt to reference a property that doesn't exist, the value returned will be undefined, so there's a lot of flexibility in how objects work. Objects can even have functions, which are often called methods when they belong to an object. We're going to take a look at how to create objects and add properties to objects, and how to retrieve properties using both dot notation and array notation, and how to delete properties as well.