The furniture having, between two lower and upper boards, each having two parallel planar surfaces and two front and rear edges, a module with one or two side walls, each having two upper and lower edges, and a rear back wall with two upper and lower edges, assembled to the side walls. The module can slide and be guided along the boards. One of the edges of each board having a longitudinal rib protruding perpendicular to its planar surfaces. The module is notched longitudinally and perpendicular to its side walls so as to slot onto the ribs of the boards and thus slide along these ribs.