2. Server
A physical computer, usually with hardware
designed for high performance and availability.
Web Server
Email Server
Database Server
3. Operating System
Software platform upon which applications “run”
and which enables and controls access to
hardware.
Examples
Windows (XP, Vista, 7, 8)
OS X
Linux
CP/M
5. Service
A program that allows clients (users or other
services) to do work.
Apache – serves web pages to clients
MySQL – stores data and answers queries
Sendmail – receives and delivers email