A wire is a metallic tube used to carry electricity and transmit electric signals. Wires connect the other components of an electrical circuit. A wire is indicated by a straight line drawn from one component to the next.
When wires are joined, it means that the charge or signal from one wire can pass to the next. For this to happen, the wires must be touching. When wires are joined, their respective lines on the circuit diagram will intersect, and a small, circular dot will be put over their intersection point.
When wires are not joined, they are not touching and electric signals cannot pass from one wire to the next. Sometimes, for the sake of a circuit diagram, it is necessary for wires lines to intersect even though the wires are not connected. When this happens, there will be no dot at the point where the wire lines intersect.