Mini display port is simply a smaller version of the display port, mini display port is mainly used on MAC computers but other manufacturers may adopt this type of connector.
The mini display port to DVI adapter will allow you to connect a high definition monitor, Projector or LCD TV to a MacBook, MacBook Pro or a MacBook Air with a mini display port connection.
Please note that while it has a DVI-I connector, this is for digital displays only.
Note also, this is a passive adapter - for AMD Eyefinity displays use an Active type (eg part 34020)