T-SQL TRUNCATE command deletes all records in the table. Apart from DELETE (more in article SQL DELETE) command, there is no possibility to filter which record to delete. It is all or nothing.
Truncate is on the other hand much faster compared to DELETE since it writes less into transaction log.
TRUNCATE TABLE dbo.Table;
First possibility is optional. When processing this command, table gets basically deleted (DROP TABLE) and created again (CREATE TABLE) without putting load on transaction log. More on truncate on Microsoft web