A computer, or any other device that connects to a network (local or Internet), must be properly configured to communicate on that network. Since DHCP allows that configuration to happen automatically, it's used in almost every device that connects to a network including computers, switches, smartphones, etc.
A DHCP server is required to issue unique IP addresses and automatically configure other network information. In most home and small businesses, the router acts as the DHCP server. In large networks, a single computer might act as the DHCP server.
Important: In most cases, when a device has an IP address assigned by a DHCP server, that IP address will change each time the device joins the network. An IP address assigned by a DHCP server is called a dynamic IP address. A manually assigned IP address is called a static IP address.