All

All is a setting used for certain options. In Part and related functions, All specifies all parts at a particular level.

Basic Usage

Extracting all elements at a specific level:

list = {{a, b}, {c, d}, {e, f}};
list[[All, 1]]
(* {a, c, e} *)

Using All to select entire rows or columns:

matrix = {{1, 2, 3}, {4, 5, 6}};
matrix[[All, 2]]
(* {2, 5} *)

All in options to apply settings to all elements:

Plot[{Sin[x], Cos[x]}, {x, 0, 2 Pi}, PlotStyle -> All]

Please visit the official Wolfram Language Reference for more details.