SQL Server - Multiple FROM keywords?

Question

The search term is to ambiguous for google aparently. I am looking at a SQL call and it has 2 FROM keywords? I've never seen this before, can someone explain?

SELECT TOP(5)  SUM(column) AS column, column
FROM ( SELECT DISTINCT column, column, column
FROM ((((((table table 
INNER JOIN table table ON (column = column
AND column = 2 
AND column != '' )) 
INNER JOIN table table ON (column   = column 
AND (column = 144 OR column = 159 OR column = 162 OR column = 164 OR column = 163 OR column  = 1 OR column = 2 OR column = 122 OR column = 155 OR column = 156 )))
inner join table table ON (column = column 
AND column  = 0 ))
INNER JOIN table  ON (column = column  ))
INNER JOIN table table ON ( column  = column  
AND (column   = 102 OR column  = 103 )))
INNER JOIN table table ON (column  = column  ))) TempTable  
GROUP BY column  ORDER BY column  desc 

You will note the multiple FROM keywords. It runs just fine. Just curious to what the purpose is.

Answer 1

This is called as subquery. You can use subquery within your main query So subquery made the multiple FORM clause.