Most of us can’t define it easily since comfort is such a personal thing. YOU KNOW IT WHEN YOU EXPERIENCE IT……AND YOU CERTAINLY KNOW IT WHEN YOU DON’T!!
We know that many seating surfaces we use in our daily lives are downright uncomfortable. In general the harder the sitting surface the greater the discomfort, which will usually increase as the sitting area gets smaller for any given surface material. The primary sources of discomfort are pressure points, causing circulation cut-off, where our body weight exerts localized pressure at various points on the seat.The highest pressure points usually occur under the pelvic "sitz" bones and/or the tail bone with discomfort also being a function of body weight and skin condition of the sitter..
Generally, the longer we sit in one position the more discomfort and fatigue we experience whether sitting in an office chair, in a vehicle on a long commute or in many other daily sitting situations. This discomfort is often experienced even more by individuals with health related issues like low back pain, arthritic or degenerative hips, poor blood circulation in the legs, and skin related conditions such as varicose veins or hemerroids etc.