It enables the operator to drill or cut work at exact intervals around a fixed (usually horizontal or vertical) axis.
The actual table is a precision-machined disc to which the work piece is clamped (T slots are generally provided for this purpose).
A graduated dial and, often, a vernier scale enable the operator to position the table, and thus the work affixed to it with great accuracy.
From this point, the secondary table can be offset in either the X or Y direction to set the cutter the desired distance from the workpiece's center.
Rotary tables have many applications, including being used in the manufacture and inspection process of important elements in aerospace, automation and scientific industries.