A client.
The computer on a network that requests resources from the server is called the client. The server may also be used to implement administrative security for the client computers.
Server
A
The applications installed help the networked server manage requests from multiple clients for different services. The server receives the requests and delegates them.
A Web Server.
concurrent server is a server which can handle multiple requests at a time.
Server's function is to respond for the client's application requests
There are no friend requests in Minecraft unless the server you are on has a specific mod for it. If so, ask around the server for specific instructions.
Yes. A server is the main component (besides the cables, hubs, and NICs) of a network. The server, as its name suggests, "serves up" resources to the network for client workstations to access. The Administrator account on the server is able to manage which normal users get to access the resources and also manages which resources they get to access and what they can do to them.
An application or browser
Client.
A server waits for a request by a client. When the client sends the requests, the server answers to it. Examples are file servers, that listen to requests from clients wanting to save or retrieve files; print servers that wait for requests to print (and then print them); DHCP servers that wait for requests to provide IP addresses; etc.