ConnectApi (Chatter in Apex): New and Changed Classes and Enums
Many Chatter REST API resource actions are exposed as static methods on Apex classes in the ConnectApi namespace. These methods use other ConnectApi classes to input and return information. The ConnectApi namespace is referred to as Chatter in Apex.
In Apex, you can access some Chatter data using SOQL queries and objects. However, it’s simpler to expose Chatter data in ConnectApi classes, and data is localized and structured for display. For example, instead of making several calls to access and assemble a feed, you can do it with a single call.