In the article http://www.thehindu.com/sci-tech/science/the-legacy-of-srinivasa-ramanujan/article2746988.ece, it was mentioned that
"This conjecture, later called Ramanujan's conjecture, came to play a pivotal role in the towering edifice known as the Langlands program, a far-reaching program articulated by R.P. Langlands in the 1970s."
How does Ramanujan conjecture play a role in the development of the Langlands program?
Ramanujan Conjecture: http://en.wikipedia.org/wiki/Ramanujan-Petersson_conjecture