Which commands are there that one can use to define new commands in (La)TeX?
\DeclareRobustCommand[*], and ...?
(And I've seen things like
The LaTeX "official" interface provides
All these commands define one or more commands (some only for internal usage) and provide tests for avoiding clobbering of existing commands. There's also
The kernel has many other command-defining macros:
Of these, only the first one is commonly used in LaTeX programming (it shouldn't be used indiscriminately as a replacement of
Some additional packages provide new functions:
are commonly found, but there are scores of other command-defining functions in the hundreds of packages around.
Another commonly used utility for defining commands is the primitive
provided by the
(look at the documentation for a description).
Eventually, all of these command-defining functions boil down to the primitive commands
but a description of these would require writing a chapter of a book; refer to the TeXbook or to TeX by Topic