I guess you use a
{figure}
environment. (Click on this highlighted word to learn more).
Figures are floating objects, which means that LaTeX places them automatically where they fit best, from a typographically point of view and especially for good page breaks.
Imagine, there's 4 cm space left on the page, but your picture has a height of 4.5 cm. If you would insist on staying at the same position within the text, there would be 4 cm white space, the figure on the next page, then comes the following text. But LaTeX does it better: it let's the figure float to the next page, while the following text already continues to fill the nearly empty page, so there's no 4 cm white space. That's a great feature especially for extensive books with many figures!
If you look at books, you will see, that figures are usually well placed, and they are referred to by figure number from within the text. With LaTeX, that's automatic placement - otherwise, if you do figure placement manually, you have to adjust all figure positions in the document again each time you add or remove text at the beginning - or somewhere.
You can ease figure placement by adding positioning options, allowing as many positions as possible. Try:
Code: Select all
\begin{figure}[htbp]
\centering
\includegraphics{filename}
\caption{caption text}
\label{fig:label}
\end{figure}
Stefan