There are two types of multifilament leaders, braided and furled.
Braided leaders have sections of braided monofilament line tied together that provide the tapering such as a section of 50 lb braided mono tied to the next section of 30 lb braided monofilament line.
Furled leaders also have several sections containing multiple filaments of line that taper. However these sections are not separate individual lines that are tied together. Rather they are a single thread or line that is looped on round pegs multiple times so they interlock, and then twisted so that the twists hold the sections together. The number of loops of thread determine the tapering. Furling refers to the "rolling" or twisting of the line around itself.
A Case for the Furled Leader | MidCurrent