Backslash-space, \

This section refers to the command consisting of two characters, a backslash followed by a space. Synopsis:

\    

Produce a space. By default it produces white space of length 3.33333pt plus 1.66666pt minus 1.11111pt.

When you type one or more blanks between words, LaTeX produces white space. But that is different than an explicit space. This illustrates.

\begin{tabular}{l}
One blank: makes some space \\
Three blanks:   in a row \\
Three spaces:\ \ \ in a row \\
\end{tabular}

On the first line LaTeX puts some space after the colon. On the second line LaTeX collapses the three blanks to output one whitespace, so you end with the same space after the colon as in the first line. LaTeX would similarly collapse a blank followed by a tab, or a blank and a newline and a blank. However, the bottom line asks for three spaces so the white area is wider. That is, the backslash-space command creates a fixed amount of horizontal space. (Note that you can define a horizontal space of any width at all with \hspace; see \hspace.)

The backslash-space command has two main uses. It is often used after control sequences to keep them from gobbling the space that follows, as in \TeX\ is nice. (But using curly parentheses, as in \TeX{} is best, has the advantage of still working if the next character is a period.) The other common use is that it marks a period as ending an abbreviation instead of ending a sentence, as in So says Prof.\ Smith or Jones et al.\ (1993) (see \@).

Under normal circumstances, \tab and \newline are equivalent to backslash-space, \ .