The world’s “first” communications satellite.
This is what NASA says about the matter:
NASA’s Chief of Communications Satellite Programs wrote in 1966:
Although not the first communications satellite, Telstar is the best known of all and is probably considered by most observers to have ushered in the era of satellite communications. This impression was a result of the tremendous impact upon the public by the first transmission of live television across the Atlantic Ocean. Telstar I was launched on July 10, 1962, and on that same day live television pictures originating in the United States were received in France. (Jaffe, pg. 107)