The role of the backrest chair.

Update:04 Aug 2016
Summary:

What is the role of the backrest chair ? A good chair, […]

What is the role of the backrest chair ? A good chair, the backrest is very important.

Generally speaking, for a chair, the backrest is not a necessary part. If the user has a large range of activities and wants to be able to flexibly turn and pick up the items, he or she can choose a chair without a backrest.

The backrest preferably supports all or part of the waist, back and neck. The longer you sit, the better your support will be.
From ergonomics. The most comfortable sitting position is to tilt back 45 degrees.
A backrest chair can be determined for the comfort and practicality of the chair.