1. A lighting system comprising:a plurality of lighting units and at least one joint which joins two or more units; the joint comprising a central support extending along a first rotation axis (R1) and two or more arms which extend radially from the support and are hinged in a rotary manner to the support to rotate with respect to the support about the first rotation axis (R1);
wherein each arm is hinged in a rotary manner about a second rotation axis (R2), orthogonal to the first rotation axis (R1), to a connection head fixed to a lighting unit;
wherein the support comprises a cap coupled to a flange of the support above the two or more arms extending radially from the support, the cap substantially comprising an inverted cup shape and being provided with at least one entry opening passing through an upper wall for the passage of one or more cables; and
wherein the joint comprises internal passages, formed inside the cap and each arm, between the entry opening and respective exit openings formed on respective connection heads, so as to house, inside the joint, one or more cables.