With the advent of digital era, nowadays images are multidimensional numerical data that can be processed and analyzed quantitatively to extract more information. ImageJ/Fiji open source software (imagej.net/) is a powerful tool available to process and analyze digital images. Moreover, it also allow the automation of image analysis with custom macros and plugins. With this course we intend to give a general introduction to ImageJ/Fiji, show how to use it to extract quantitative data and how to write simple macros. This course will be focused in the analysis of light microscopy images, but is targeted to all people engaged in research, that wants to start using ImageJ/Fiji for image analysis in general.