The goal of this page is to explain buzzwords or Matrix specific words on a high level for newcomers.
A Homeserver is the term for the Server a user logs in to. For example, if you have the Matrix ID
@xyz:example.com your homeserver would be
A Matrix ID (also called MXID) is the matrix equivalent of an Email address. It is commonly of the form
@<username>:<homeserver> and represents the true ID used within the protocol representing a user. This is not to be confused with the username, which is also commonly called localpart in the Matrix world, since the username is only scoped to your local homeserver. It may be reused by someone else on another server.
Spaces are Groups of Chatrooms. You can compare them with Folders, where a Space is a Directory and a Room is a File. Each space can have subspaces and subrooms. A core difference to folders however is that Rooms from subspaces usually in current Client implementations are propagated upwards in a tree. Allowing you to filter rooms as you go down the tree and seeing multiple branches as you go up the tree.
An additional feature of spaces is that rooms can be part of a space while not being visible within the space unless you already entered the room. In this, the space is a parent of a room, however at the same time the room is not a child of the space. This effectively hides the room from the space unless you are already part of the room, and is useful in combination with knocking.
A widget is an embedded website. This can be as simple as just embedding a website like Etherpad into a room and go as far as integrating a video chat solution like Jitsi where the username is pushed to the included website. Furthermore, a widget can ask for access of specific event types and therefor tightly integrate into a chatroom, allowing for combination of different Matrix features.