The NSA was founded in the early 1950s to be the primary signals intelligence (SigInt) branch of the US Government, largely to gather information which would be of strategic importance in the Cold War.  You might look at the NSA as a SigInt counterpart to the National Reconnaissance Office (NRO), which runs most of the spy satellites and other strategic imagery.  The Wikipedia article on the NSA is quite good.[1]<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;National_Security_Agency" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;National_Security_Agency</a>