For reference (and DEK entertainment), from the TeX Book (chapter 3 Controlling TeX, p 8):
It is usually unnecessary for you to use “control space,” since
control sequences aren't often needed at the ends of words. But here's
an example that might shed some light on the matter: This manual
itself has been typeset by TeX, and one of the things that occurs
fairly often is the tricky logo
\TeX, which requires backspacing and
lowering the E. There's a special control word
that produces the half-dozen or so instructions necessary to typeset
\TeX. When a phrase like
\TeX\ ignores spaces after control words.
is desired, the manuscript renders it as follows:
TeX ignores spaces after control words.
Notice the extra
\TeX; this produces the control space
that is necessary because TeX ignores spaces after control words.
Without this extra
\, the result would have been
TeXignores spaces after control words.
On the other hand, you can't simply put
\TeX in all
contexts. For example, consider the phrase
the logo `TeX'.
In this case an extra backslash doesn't work at all; in fact, you get
a curious result if you type
the logo `\TeX\'.
Can you guess what happens? Answer: The
\' is a control sequence
denoting an acute accent, as in our
P\'olya example above; the
effect is therefore to put an accent over the next nonblank character,
which happens to be a period. In other words, you get an accented
Computers are good at following instructions, but not at reading your