Without data replication, multiple sites would have slow access to their data. Having multiple sites around the world with the same data, load balancing becomes a reality, and the data is always reachable. In brief, if you are a Publisher, you are a server that makes its data available for replication to other servers. The Publisher specifies which data is to be replicated and flags changes made to the data since the last synchronisation process occurred. To make sure this data integrity is maintained, any data element that is replicated has one and only one Publisher.
Subscribers are servers that store the replicated data and receive updates from publishers.
A Publication is simply a collection of Articles, and an Article is a grouping of data to be replicated. This can be an entire table, specific columns of a table, specific rows of data, or a combination of both. When you subscribe, you subscribe to Publications not individual articles.