TCP and UDP
 TCP is a connection oriented protocol
 UDP  is a connection less protocol

TCP and UDP
 TCP is a connection oriented protocol
 UDP  is a connection less protocol

Ports are used to identify a application process on a
particular system.Think in the direction of ,how your
application programm is identifed by your system,while  many
other process running on your sysytem.

ports r used by the protocols of varies layers in a 
system.If we want perticular service from the port ,we have 
to send message to that perticular port by using tcp/udp.

Port is a special number present in the header of a data
packet. Ports are typically used to map data to a particular
process running on a system.These are divided into three
ranges.1.Well known(0-1023) 2.Registered(1024-49151)
3.Dynamic/private ports(49152-65535).

For reliable connection using TCP, transport layer assigns 
a unique set of numbers for each connection.That i sknown 
as port Number.

ports r used to identify a application process in a 
particular system.

  UDP(user datagram protocol) for connectionless protocol.
TCP(transmission control protocol) for connection oriented 
protocol

To explain the concept of port, i use the one example,

You are writing a letter to your friend, in this letter you
will write the Full address details such as Door
Number,Village Name, etc....

Take this example, in networking level, Here the Village
name is like IP address and Door Number is like Port. 

Why you are mentioning the door number in the letter,
because in the village there are number of houses, to find
your friends house the Door Number is needed, Like that in
computer there are many process running simultaneously, to
identify particular process, port number is mainly used. 

there are totally 65,535 port numbers are available, Some
port numbers are known as well known port number, this is
mainly used as server port number.