The humble tiff file is used for storing raster data, this talk will take a dive into the internal structure of the format. The humble tiff file is used for storing raster data, when creating them there are many options, it can be difficult to know exactly what options mean and what the implications of them. This talk will dive into the internals of the file format, explaining the overall structure and the historical reasons for some of the options. Then we will go deeper into the bits and bytes and why things are laid out the way they are. This talk will make use of the tiffhax project to explain things.