A left angle bracket delimiter used to denote sequences, inner products, or bra-ket notation in mathematics and physics.
Examples
Inner product notation
\langle u, v \rangle = \sum_{i=1}^n u_i v_i
Average or expected value
\langle X \rangle = \frac{1}{N} \sum_{i=1}^N x_i
Generator notation in group theory
G = \langle a, b \mid a^2 = b^3 = e \rangle