The term 'Sigma Follower' refers to two Greek letters, TAU (Τ) and CHI (Χ), which are often used in mathematics and science. TAU is the 19th letter of the Greek alphabet and is represented by the symbol τ, while CHI is the 22nd letter of the Greek alphabet and is represented by the symbol χ. Both letters are used to represent various mathematical and scientific concepts, such as angles, ratios, and constants. In addition, they are also used in various fields such as engineering, physics, and chemistry.