what is the song edge of glory about
It speaks of the very last moments of life.
The Edge of Glory
The song was released on May 9, 2011 as the album's third single. Initially released as one of two promotional singles for "Born This Way", it shortly became a single following its success in digital outlets worldwide. The song was written and produced by Gaga and Fernando Garibay, and is a pop, electro-rock, and disco song that speaks of the very last moments of life. According to Gaga, lyrical inspiration came from the death of her grandfather, who died in September 2010. 
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The Edge of Glory [SEP] Introduction
In the United States, it peaked at number three on the "Billboard" Hot 100, becoming Gaga's tenth consecutive top-ten single in the United States. A music video for the song was filmed in late May, co-directed by the singer and her production team, Haus of Gaga. The video is simple in contrast to much of Gaga's previous work, and portrays her dancing on a fire-escape and walking on a lonely street. Differences include the lack of intricate choreography and back-up dancers, as well as using only one outfit designed by Versace. Critics lauded the simplicity of the video, while comparing it to the works of Michael Jackson, Janet Jackson and Madonna.