The jacquard is a shedding device attached to looms that controls individual warp threads to produce complex designs without heddles. It can create any shape and control up to 1800 threads at once, making it suitable for intricate patterns. The jacquard is the most complex and costly mechanism compared to dobbies and tappets, which control threads collectively and produce simpler designs. Key differences include how many threads are controlled, placement on or below the loom, and types of designs produced.