Subscript

Subscript[x, y] is an object that formats as x with subscript y.

Subscript[x, y1, y2, ...] formats with multiple subscripts.

Examples

Create a subscript:

Subscript[x, 1]
(* x₁ *)

Multiple subscripts:

Subscript[a, i, j]
(* aᵢⱼ *)

Please visit the official Wolfram Language Reference for more details.