Documentation

Mathematica Teacher's Edition

Built-in Functions

Lists and Matrices

List Operations

Insert

Insert[list, elem, n] inserts elem at position n in list. If n is negative, the position is counted from the end.
Insert[expr, elem, i, j, ... ] inserts elem at position i, j, ... in expr.
Insert[expr, elem, , , ... , , , ... , ... ] inserts elem at several positions.

Examples: Insert[a, b, c, x, 2].
Insert[a, b, c, x, 1, -1].
Insert[a, b, c, d, x, 2, 1].
list can have any head, not necessarily List.
See The Mathematica Book on the web: Section 1.8.6.
See also: Prepend, Append, Take, Drop, Delete, ReplacePart, Position.

Further Examples