SQL Server optimization series - query recompilation gotchas

What causes the query to recompile? Is it a good sign or bad sign for performance? How frequently should I recompile the stored procedures? Does a reindex cause SP to recompile when it is executed next time? These are quick questions raised in the recent times that I have recieved via emails/forums/user groups, the real response for the above questions varies on version to version. By default the optimization of stored procedure - recompile: will occur when that SP is executed for first time and...(<a href="http://sqlserver-qa.net/blogs/perftune/archive/2011/04/05/6254.aspx">read more</a>)<img src="http://sqlserver-qa.net/aggbug.aspx?PostID=6254" width="1" height="1">