Monitors have different types of connections to hook it to a computer. Some connections are analog, while new technology lets a user attach a monitor digitally to get the best possible picture available as output.
The Video Graphics Array analog connection has been around since 1987, and it can be recognized by the 15-pin configuration. Most VGA ports on the computer are blue.
One different type of connection for a monitor that gives better picture quality than VGA is S-Video. This is a 5-pin setup that typically has yellow or black ports.
Since the mid-2000's, the Digital Video Interface connection has become a common port on computers and monitors. There are 24 pins on this connection, and the port is usually white or off-white.
For a true digital connection with precise color, definition and sound, use an HDMI cable. This is a port that resembles a USB port, but it is slightly tapered.
To ensure a user receives the best possible picture, connect the monitor to the computer using the same ports; that way, no conversion---which could degrade the video signal---is needed.