A common approach for using images in latex documents is adding \usepackage{graphicx} to the preamble and of myfile.tex inserting image in the following text with \includegraphics{my_image.eps} ( the image type can be different including png, jpg and even .pdf).
If the image type is a some kind of mathematical graph or drawing/scheme one could use TikZ or PSTricks to draw it. However, this approach results in “double work”, e.g. even on a minor change one needs first to compile my_image.tex to my_image.eps, then recompile myfile.tex to update picture in the resulting pdf. Additionally this method has drawbacks, such as changing font size of the text in on resizing the my_image.eps.
One of the possible ways to solve this problem is using standalone package. It allows inserting my_image.tex file in a myfile.tex as an image, while keeping the possibility to compile my_image.tex as a standalone image. Example file listings can be seen in a dedicated gists.
This text is mostly based on the following discussion on tex.stackexchange.
cat /dev/head 