A binary operator representing multiplication, scalar products, or composition in a more visually subtle way than \times.
Examples
Multiplication of numbers
2 \cdot 3 = 6
Scalar multiplication with vector
5 \cdot \vec{v} = (5x, 5y, 5z)
Dot product of vectors
\vec{a} \cdot \vec{b} = a_1b_1 + a_2b_2 + a_3b_3