In its simplest form: body fat is the amount of fat in your body, compared to everything else. Everything else includes your organs, muscles, bones, tendons, water, and so on.
Both men and women carry different amounts of body fat percentage this is due to being well, different.
A super ripped male body builder who is minimizing body fat percentage could have a percentage down as low as 3-4%, while a super ripped female body builder who is minimizing body fat percentage would only get as low as 8-9%. A male athlete could be in fantastic shape and have 10% body fat, while a women at comparable level of athleticism and appearance might be at 18-20% body fat. To take the comparison to the other end of the spectrum, an overweight male at 30% will look vastly different than an overweight woman at 30%.
In what I’m sure is news to nobody, body fat is essential to survival – fat protects your internal organs, provides you with necessary energy stores in times of peril, and more.
“Essential fat” means the minimal amount of fat required for survival – Anything less than this amount would mostly likely result in organ failure, but even approaching this amount of body fat is dangerous. It’s for this reason that bodybuilders, who can minimize their body fat to the “essential fat” level only do so when prepping for a show – during the rest of the year they maintain a higher body fat percentage so that they can stay healthy and function properly.