LaTeX provides a number of different paragraph-making environments. Each environment begins and ends in the same manner.
\begin{environment-name}
....
....
\end{environment-name}
Blank lines before the \begin{} or after the \end{} cause a
paragraph break before or after the environment.
Blank lines after the \begin{} or before the \end{} are
ignored.
All declarations have an environment of the same name. However, the reverse does not always work. For example, {\abstract Abstract text ... .} may not give correct paragraph breaks.