Question : explain T-SQL query to me

Can somebody explain this SQL query to me? what is it doing?

DECLARE @CollectionID int      

SELECT @CollectionID= C2.CollectionID
FROM Collections C1
      INNER JOIN Collections C2 on C1.CollectionID = C2.ParentID
WHERE C1.Title= '09-0274'
      --AND C1.CompanyID= 1 and C2.Title LIKE 'Vendor-'  + '240635'
      AND C1.CompanyID= 1 and C2.Title LIKE '%240634%'

Answer : explain T-SQL query to me

This type of JOIN is called 'Self Join' - Joining a table with itself.
http://msdn.microsoft.com/en-us/library/ms177490.aspx

In your case, 'ParentID' column is JOINed to 'CollectionID' column of the same table.

Raj