What is Cascade and Restrict when we use DROP table in SQL SERVER ?

When we are using Drop table in SQL the syntax is simple.
Drop table table_name(CASCADE / RESTRICT)
We use cascade to drop table although it have some dependencies just like triggers,stroeprocrdure,primarykey,foreignkey it will delete first.
But if we use restrict a error message is shown on using of DROP if the table have relation Trigger,storeprocedure.