A VESA standard for the position of screw holes in the back of a monitor or TV for attachment to a wall mount or desktop arm. Introduced in 1997 as the Flat Panel Monitor Physical Mounting Interface (FPMPMI), the original standard became part D in a variety of specifications (B, C, D, E and F) primarily based on maximum weight.
For 27" to 55" Flat Panels
Many VESA wall mounts such as this one from VideoSecu have a variety of holes to accommodate different VESA patterns. (Image courtesy of Amazon.com.)