Head[expr] gives the head of expr.

Heads is an option for functions which use level specifications that specifies whether heads of expressions should be included.

In most cases, you want the head f of a Mathematica expression like f[x] to be a single symbol. There are, however, some important applications of heads that are not symbols. ...

TableHeadings is an option for TableForm and MatrixForm which gives the labels to be printed for entries in each dimension of a table or matrix.

Mathematica provides great flexibility for displaying and styling headings in a table. You can use Prepend or ArrayFlatten to add headings to rows and columns and then use ...

Mathematica handles many different kinds of things: mathematical formulas, lists, and graphics, to name a few. Although they often look very different, Mathematica represents ...

Arrowheads[spec] is a graphics directive specifying that arrows that follow should have arrowheads with sizes, positions, and forms specified by spec.

Operate[p, f[x, y]] gives p[f][x, y]. Operate[p, expr, n] applies p at level n in the head of expr.

A foundational idea in Mathematica is that all expressions—whatever they may represent—ultimately have a uniform tree-like structure.

Expressions are the main type of data in Mathematica. Expressions can be written in the form h[e_1,e_2,…]. The object h is known generically as the head of the expression. ...