Axcess magazine interviewed Reznor after the release of The Downward Spiral in 1994. They asked him how he came up with the name Nine Inch Nails and this was his reply:
"I don't know if you've ever tried to think of band names, but usually you think you have a great one and you look at it the next day and it's stupid. I had about 200 of those. Nine Inch Nails lasted the two week test, looked great in print, and could be abbreviated easily. It really doesn't have any literal meaning. It seemed kind of frightening. [In his best he-man voice] Tough and manly! It's a curse trying to come up with band names."
The Nine Inch Nails "NI?" logo was designed so that Trent Reznor could have a design that in his own words "looked cool on my leather jacket." It is also interesting to note that the font used in the "NI?" logo was modeled after the font used in the album art for the Talking Heads' album Remain In Light.
NI?'s sound has variously been described as alternative, electronica, heavy metal, rock, synth pop, or, most commonly, industrial. Regarding his music being categorized as industrial, Reznor had this to say in a 1994 Axcess magazine interview:
"What was originally called industrial music was about 20 years ago Throbbing Gristle and Test Dept. We have very little to do with it other than there is noise in my music and there is noise in theirs. I'm working in the context of a pop song structure whereas those bands didn't. And because someone didn't come up with a new name that separates those two somewhat unrelated genres, it tends to irritate all the old school fans waving their flags of alternativeness and obscurity. So, I'd say I've borrowed from certain styles and bands like that."
NI?'s songs cover a range of genres; as a body of work, they cannot be pigeonholed. "The Perfect Drug" has the flavor of drum and bass, vocals in "Down in It" seem influenced by early rap & hip-hop, "Happiness in Slavery" is in the vein of Skinny Puppy and Ministry, "The Frail" is a melancholy piano piece, and most of Pretty Hate Machine could be considered dark synth pop.
--- from the official Nine Inch Nails website