When you create a new database, SQL Server creates a copy of the Model database and gives it the name of your new database. When you issue the create command:
CREATE Database NewDB GO
SQL Server makes a copy of the already existing Model database. This can be helpful to understand, because you can make changes to the Model database, knowing that as you create a new database it will be a copy of the Model. If you have stored procedures or functions that you always want in a new database, put them in the Model database.