What is inside a server
CPU & memory: one or more processors and large-capacity ECC memory. Storage: SSDs or HDDs, usually behind a RAID controller. Network: multiple NICs for redundancy and throughput. BMC & power: management controller and redundant power supplies. A server is a computer that serves other computers over the network and is the workhorse in data centers running applications, databases, and virtual machines.
How servers are built and used
By role: web, application, database, file, mail, and virtualization (hypervisor) hosts. By form factor: rack servers (measured in U), blade servers in a shared chassis, tower servers for smaller sites, and hyper-converged nodes that fuse compute and storage.
Server reliability depends on its hardware
At a scale of thousands of servers, component failures — fans, power supplies, disks, memory, NICs — accumulate into hundreds a year. Most monitoring only sees a server once the OS is up. By monitoring the underlying hardware through the management controller, you can catch these failures before they take down applications.