Format with extension .bmp is known as Windows Bitmap. It is also known as .dib, which in English means Device-Independent Bitmap. It is graphical format which is using raster graphics. It can be opened in almost every graphic editor, so this file format can be opened on Windows and even on MacOS.
This file type was created in 1988, where it belonged to operating system OS/2. Later on was it used by Microsoft for their operating system called Windows 3.0. Few years later it was updated for 32bit version of operating system OS/2. The main advantage is its simplicity and free distribution. That makes him very useful file type, so it´s not problem to implement it in almost every graphic editor, which causes that it is part of them. This file format uses raster graphic, which means that it draws every pixel after pixel on the screen unlike vector graphics that, which uses geometrical shapes.
To open files saved in .bmp file format you can use casual picture viewer from operating system Windows.