What is the difference between tcp and udp protocol ?

Very easy to understand.

Transmission Control Protocol (TCP): TCP is one of the main protocols in TCP/IP networks. TCP will verify whether the packet reach in the destination or not. if it doesn't get reply that the package reach safely, it will resent the same package.

eg. for TCP : Web, SMTP, sending mail

User Datagram Protocol (UDP). UDP is also a protocol for sharing the data packages. It doesn’t check whether the packet reach the destination safely, if the packet not reach the destination it won’t resent the package.

eg. for UDP: Media streaming (lost frames are ok)

for more details go through the web page

http://www.diffen.com/difference/TCP_vs_UDP

TCP get acknowledgement from the receiver and it is connnection oriented, hence it is most reliable

UDP does not require any acknowledgement from receiver. it is unreliable.

Video streaming is a classic example of UDP. HTTP is an example for TCP

Agree with all the respected members, there is no contradiction in saying UDP is not so reliable compared to TCP. but it doesnt mean that UDP is not useful its more efficient in some scenarios or situations where the quality doesn't really matters.Like in on going call of skype even if you lost packets or the values where it gets updated very frequent, network gaming or just a simple hello packet (and many others) in all of these cases UDP would be much more proffered than TCP.

And with above all yes TCP is reliable and is used most.

Best real life example for TCP would be Web, Emails where every bit is important and needs to be received/transferred correctly, as for UDP the best example would be video streaming where even if we lost some bits it would not matter. Hope this helps

Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)is a transportation protocol that is one of the core protocols of the Internet protocol suite. Both TCP and UDP work at transport layer TCP/IP model and both have very different usage.

TCP (Transmission Control Protocol) is the most commonly used protocol on the Internet. The reason for this is because TCP offers error correction. When the TCP protocol is used there is a “guaranteed delivery.” This is due largely in part to a method called “flow control.” Flow control determines when data needs to be re-sent, and stops the flow of data until previous packets are successfully transferred. This works because if a packet of data is sent, a collision may occur. When this happens, the client re-requests the packet from the server until the whole packet is complete and is identical to its original.

UDP (User Datagram Protocol) is anther commonly used protocol on the Internet. However, UDP is never used to send important data such as webpages, database information, etc; UDP is commonly used for streaming audio and video. Streaming media such as Windows Media audio files (.WMA) , Real Player (.RM), and others use UDP because it offers speed! The reason UDP is faster than TCP is because there is no form of flow control or error correction. The data sent over the Internet is affected by collisions, and errors will be present. Remember that UDP is only concerned with speed. This is the main reason why streaming media is not high quality

Both TCP and UDP are protocols used for sending bits of data — known as packets — over the Internet. They both build on top of the Internet protocol. In other words, whether you're sending a packet viaTCP or UDP, that packet is sent to an IP address.

TCP and UDP are transport Layer protocols. There are lot of protocols which are used on this layer but when it comes to the programs on the network these two protocols are used. Following are the difference between both.

TCP:

1. Connection oriented protocol

2. Use Sequence numbers

3. Reliable (Use Acks)

UDP:

1. Connection less

2. Best effort delivery, no sequence numbers

3. Unreliable (No Acks)

In simple terms

UDP says I hope data gets to the destination while TCP says I know data Got to the destination  (Three way handshake, ack)