M for Macro
This is a pretty common term in the photography circuit. A photograph, where we take photos of small subjects, and the photos come out to be bigger than the subjects and in sharp details, that is a macro photograph. For achieving this, there are special lens available. Close up filters, extension tubes and lens reversal are also put to use. Each have their own pros and cons. Do note, while in Macro, the DOF offered is extremely shallow.
Check out a refreshing take on macro, here.