Tactical pants are closely related to cargo pants

Cargo pants

Cargo pants are loosely-cut pants designed for tough, outdoor activities distinguished by multiple cargo pockets.A cargo pocket is a form patch pocket with accordion folds for increased capacity closed with a flap secured by snap, button, or Velcro common on battledress and hunting clothing.Cargo...

, but with some technical modifications, and specially designed as everyday armor for a range of professions from EMTs, FBI and SWAT Team agents, law enforcement officers, and military and fire professionals.

These durable pants

Trousers

Trousers are an item of clothing worn on the lower part of the body from the waist to the ankles, covering both legs separately...

were originally worn by mountain climbers, but now are made in several different styles. Tactical pants typically are solid in color, distinguishing them from cargo pants. Made with lightweight materials (65% polyester and 35% poly cotton ripstop), the belt loops are made thick enough to support a large belt to carry the weight of a sidearm, cuffs or other equipment. External knife pockets are common, and the double reinforced seat and knees provide enhanced abrasion protection, with interior knee slots ready to accept 6mm neoprene kneepads.

Various styles can be reinforced with bar-tacks, gussets, and certain brands are even coated with Teflon.