In SQL Server, defaults are values that are automatically assigned to a column when a new row is inserted into a table, if no explicit value is provided for that column. Defaults provide a way to specify a default value that is used when a value is not explicitly provided during an insert operation.

Defaults can be defined at the column level during table creation or added later using the ALTER TABLE statement. Here are a few key points regarding defaults in SQL Server:

1. Default Constraints
2. Syntax for Defining Defaults
3. Default Values
4. Nullable Columns
5. Altering Defaults
6. Dropping Defaults                                                                                  Defaults provide a convenient way to handle scenarios where certain columns often have common or predefined values. They help ensure data consistency and can simplify data entry by automatically assigning default values when no explicit value is provided during an insert operation.