Hallelujah is a song composed by Leonard Cohen and performed by hundreds of popular music artists.
Come Christmas time you may hear another set of lyrics that have been composed as a seasonal (Christian) version.
If you want to know more about the background of the song this Mental Floss article has a few facts I hadn’t read before.
The article makes the observation that the many, many, many (too many) renditions of the song might make it seem overexposed, but the word at the heart of the song “Hallelujah” is both an invitation to, as well an expression of, praise.
In 2009, after the song appeared in Zack Snyder’s Watchmen, Cohen agreed with a critic who called for a moratorium on covers. “I think it’s a good song,” Cohen told The Guardian. “But too many people sing it.”
Except “Hallelujah” is a song that urges everyone to sing. That’s kind of the point. The title is from a compound Hebrew word comprising hallelu, to praise joyously, and yah, the name of god. As writer Alan Light explains in his 2013 book The Holy or the Broken: Leonard Cohen, Jeff Buckley, and the Unlikely Ascent of “Hallelujah,” the word hallelujah was originally an imperative—a command to praise the Lord. In the Christian tradition, it’s less an imperative than an expression of joy: “Hallelujah!” Cohen seemingly plays on both meanings.