WITH common_table_expression (Transact-SQL)

Can someone explain what 'WITH common_table_expression' for Transact-SQL is and why/when would be a good time to use? I have read the explanation on MSDN, but it doesn't really make much sense to me.
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computerstreberAsked:
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Faiga DiegelSr Database EngineerCommented:
CTEs acts like a temporary view or vitual table. It is very useful when writing recursive queries.

Ive been using these as reference for creating CTEs:

http://msdn2.microsoft.com/en-us/library/ms190766.aspx
http://www.sql-server-performance.com/articles/dev/cte_sql2005_p1.aspx
http://www.simple-talk.com/sql/sql-server-2005/sql-server-2005-common-table-expressions/
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chapmandewCommented:
They can be used as view structures or "table variable like" structures.  Here is an article I wrote recently on how they can be used to recursively find blocking processes on your server:

http://blogs.techrepublic.com.com/datacenter/?p=275

Tim
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computerstreberAuthor Commented:
Those are both great response. Thank you so much.
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Microsoft SQL Server 2005

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