Blade Servers are made of a chassis (or enclosure) and one or more server blades that fit vertically into the chassis.
This configuration is designed to save space by fitting servers side by side in the chassis so that what might typically be a stack of servers is instead contained in a space only 7U, 8U or 10U high.
Blade servers accomplish this efficiency by passing off common functions such as power, cooling, networking, management and interconnections to the chassis while the blades themselves control server functions such as processing and storage.
Because individual blades are usually hot-swappable, they’re well-suited for applications such as Web hosting and cluster computing. Although cooling can be a concern when large clusters are grouped together, increasingly sophisticated environmental controls for data centres make this less of a concern.