What does ` 1 stand for in LINQ?

What does ` 1 stand for in LINQ?

References

Reference NO 1

http://stackoverflow.com/questions/2387884/what-does-this-mean-in-c-sharp-or-linq

Reference NO 2

http://stackoverflow.com/questions/10773048/what-does-any-mean-in-this-linq-query

Reference NO 3

http://stackoverflow.com/questions/2240041/what-does-this-linq-query-do

Reference NO 4

http://www.abbreviations.com/LINQ

Reference NO 5

http://www.allacronyms.com/LINQ

Reference NO 6

http://www.hanselman.com/blog/TheWeeklySourceCode52YouKeepUsingThatLINQIDunnaThinkItMeansWhatYouThinkItMeans.aspx

Reference NO 7

http://quizlet.com/20737220/pro-c-2010-chapter-13-linq-to-objects-flash-cards/

Reference NO 8

http://www.codeproject.com/Articles/84521/LINQ-for-the-Beginner