\bigskip \medskip \smallskip
These commands produce a given amount of space.
\bigskip
\vspace{bigskipamount}
, ordinarily about one line
space (with stretch and shrink).
\medskip
\vspace{medskipamount}
, ordinarily
about half of a line space (with stretch and shrink).
\smallskip
\vspace{smallskipamount}
, ordinarily about a
quarter of a line space (with stretch and shrink).
The \...amount
parameters are determined by the document class.