For those people who work at computer workstations, good office seating is essential for preventing back pain and maintaining a focus on work. Select a chair that easily adjusts in height. The range of adjustment should be enough for your particular body shape as well as the tasks you perform. For example, you may want the chair higher for keyboarding and lower for editing a document. Make sure the backrest provides enough support for your lower back.
Some chairs have adjustments for both the position and the tension of the backrest.
Before making a final chair selection, 'test drive' several for a few days each. You might find that different features are more important depending on the tasks you are performing. Try these adjustments before you purchase a chair so you can be assured that you get enough support where you need it. Use your chair adjustments, and use them often. It's not uncommon for modern task chairs to have six or more different adjustments.