A deficit deadlift is a deadlift performed while standing on a weight plate or platform, usually around one to four inches high. It's used as assistance work for those that have trouble in the first stage of the deadlift. The increased range of motion also recruits more of the posterior chain and quads.
You can even get creative with it and use farmers walk handles on either side of your platform or plate. These really challenge your grip with heavy weights.
In four months I'll be a whopping 28 years old. I know a thing or two about training and all that goes into it, but I also respect the fact that there's a hell of a lot I don't know enough about, and other topics I need to know something about that I'm not even aware of!