What does TOP 1 mean in an sql query?

Question

What does TOP 1 mean in an sql query?

SELECT TOP 1 RequestId 
FROM PublisherRequests

Answer 1

It will select the first row from the PublisherRequests table.

EDIT: [The order will be defined based on the clustered key in that table - This statement is incorrect]. Actually, according to Alex's findings, and according to BOL, the order of the rows will be arbitrary.

Reference can be found here.