I am using the command \begin{subfigure}...\end{subfigure} to insert three pictures side by side. But I would like to know how to give an space between then, since they are too close each other.
\begin{figure}
\begin{subfigure}
here's the first image
\end{subfigure}
\begin{subfigure}
here's the second image
\end{subfigure}
\begin{subfigure}
here's the third image
\end{subfigure}
\end{figure}
I suggest using subcaption
and adding some \hspace
between the images:
\documentclass{article}
\usepackage{subcaption,graphicx}
\begin{document}
\begin{figure}
\centering
\begin{subfigure}{.3\linewidth}
\centering
\includegraphics[width = \linewidth]{example-image-a}
\caption{First image}
\end{subfigure}%
\hspace{1em}% Space between image A and B
\begin{subfigure}{.3\linewidth}
\centering
\includegraphics[width = \linewidth]{example-image-b}
\caption{Second image}
\end{subfigure}%
\hspace{2em}% Space between image B and C
\begin{subfigure}{.3\linewidth}
\centering
\includegraphics[width = \linewidth]{example-image-c}
\caption{Third image}
\end{subfigure}
\caption{A number of images}
\end{figure}
\end{document}