Make-before-break and the order of operations in switching
In switchgear, the sequence matters more than the connection. Two words describe two opposite failure modes.
A switch that moves a circuit from one contact to another has a choice to make in the moment between positions. It can connect the new contact before releasing the old one, or release the old one first. Those two behaviours have names, and picking the wrong one damages equipment.
A make-before-break switch creates the new connection before breaking the old, so the two are briefly joined. A break-before-make switch does the opposite, opening the circuit completely for an instant during the transition.
Each one protects against a different problem
Inductive circuits hate being opened. Current through an inductor cannot stop instantly, and interrupting it produces a voltage spike that arcs across the opening contacts. Current transformer secondaries are the classic case, and they are switched make-before-break for exactly this reason.
Sources hate being paralleled. Briefly connecting two supplies together can produce heavy circulating current. Anything selecting between power sources is normally break-before-make, accepting a momentary gap to avoid the short.
Reading it off a drawing
The distinction is rarely obvious from a schematic symbol, so it tends to live in the switch specification rather than the diagram. When replacing a rotary switch or a selector, matching contact rating and position count is not enough. A part that is correct in every other respect will misbehave if the transition sequence is wrong.