A backrest for a chair, in particular an office chair, comprising - a base, by means of which the backrest can be or is connected to the chair, - a backrest element for providing a reclining surface for the back of a person sitting on the chair, wherein the backrest element is connected in a force-transmitting manner with the base, wherein the backrest element comprises a plurality of support elements (6, 7, 8), wherein the support elements (6, 7, 8) are set up to each support different areas of the back, wherein the support elements (6, 7, 8) each have a web spaced apart from the base as well as two opposing flanges each connected to one side of the accompanying web, wherein the flanges of a respective support element (6, 7, 8) each face the base and are indirectly or directly connected with the base, wherein the web of a respective support element (6, 7, 8) is arranged on ends of the accompanying flange spaced apart from the base, so that the support elements (6, 7, 8) are each invertedly U-shaped in relation to the base, wherein the support elements (6, 7, 8) are nested relative to each other in such a way that-in relation to a center of the reclining surface -a respective more outwardly lying support element (7, 8) frames a more inwardly lying adjacent support element (6, 7) on three sides, wherein a stiffness of the backrest element is segmented via the nesting of support elements (6, 7, 8), and the support elements (6, 7, 8) can be formed at least essentially independently of each other, wherein the support elements (6, 7, 8) each have different stiffnesses in relation to the base due to differing lengths of the flanges, so that the support elements (6, 7, 8) behave differently when exposed to a load from a back leaning against the backrest element, such that a more outwardly lying support element (7, 8) deforms more strongly than a more inwardly lying support element (6, 7) under an identical load, wherein a lumbar support is provided, which is arranged in a lower area of the backrest element, which is framed by all support elements (6, 7, 8), characterized in that the lumbar support can be or is non-destructively, detachably mounted to the remaining backrest. - a base, by means of which the backrest can be or is connected to the chair, - a backrest element for providing a reclining surface for the back of a person sitting on the chair, wherein the backrest element is connected in a force-transmitting manner with the base, wherein the backrest element comprises a plurality of support elements (6, 7, 8), wherein the support elements (6, 7, 8) are set up to each support different areas of the back, wherein the support elements (6, 7, 8) each have a web spaced apart from the base as well as two opposing flanges each connected to one side of the accompanying web, wherein the flanges of a respective support element (6, 7, 8) each face the base and are indirectly or directly connected with the base, wherein the web of a respective support element (6, 7, 8) is arranged on ends of the accompanying flange spaced apart from the base, so that the support elements (6, 7, 8) are each invertedly U-shaped in relation to the base, wherein the support elements (6, 7, 8) are nested relative to each other in such a way that-in relation to a center of the reclining surface -a respective more outwardly lying support element (7, 8) frames a more inwardly lying adjacent support element (6, 7) on three sides, wherein a stiffness of the backrest element is segmented via the nesting of support elements (6, 7, 8), and the support elements (6, 7, 8) can be formed at least essentially independently of each other, wherein the support elements (6, 7, 8) each have different stiffnesses in relation to the base due to differing lengths of the flanges, so that the support elements (6, 7, 8) behave differently when exposed to a load from a back leaning against the backrest element, such that a more outwardly lying support element (7, 8) deforms more strongly than a more inwardly lying support element (6, 7) under an identical load, wherein a lumbar support is provided, which is arranged in a lower area of the backrest element, which is framed by all support elements (6, 7, 8), characterized in that the lumbar support can be or is non-destructively, detachably mounted to the remaining backrest.