What is map transparency

[SValera]

   
What is map transparency as its make and use

[floyd86]

I think you mean a transparency map. This is a black and white image you can add to your material. The black parts of the image will be transparent in your render, while the white will be visible. With such a map you can easily make objects which are hard and time-consuming to model: like leaves, grids, hair etc
Read more about the use here: Advanced textures