UDP and TCP both are protocols used for sending bits of data over the Internet. They both build on top of the Internet protocol. Whenever you are sending a data via TCP or UDP, that data is sent to an IP address. These data are treated similarly, as they are forwarded from your computer to intermediary routers and on to the destination.

These two are not the only protocols that work on top of IP. However, they are the most widely used.

Here we are going to highlight some information about TCP and UDP and explore the differences between these different protocols.


UDP stands for User Datagram Protocol, is part of the Internet Protocol suite used by programs running on different computers on a network. UDP is used to send short messages called datagrams, but overall, it is an unreliable, connectionless protocol. UDP is officially defined in RFC 768 and was formulated by David P. Reed.


TCP stands for Transmission Control Protocol, is one of the most used protocols in digital network communications and is part of the Internet protocol suite, commonly known as the TCP/IP suite. TCP is a network communication protocol designed to send data packets over the Internet. TCP is a transport layer protocol in the OSI layer and is used to create a connection between remote computers by transporting and ensuring the delivery of messages over supporting networks and the Internet. It works in collaboration with Internet Protocol, which defines the logical location of the remote node, whereas TCP transports and ensures that the data is delivered to the correct destination.


  • Where UDP enables process-to-process communication, TCP supports host-to-host communication.

  • TCP sends individual packets and is considered a reliable transport medium; UDP sends messages, called datagrams, and is considered a best-effort mode of communications.

  • Where TCP provides error and flows control, no such mechanisms are supported in UDP.

  • UDP is considered a connectionless protocol because it doesn't require a virtual circuit to be established before any data transfer occurs.

  • UDP provides two services not provided by the IP layer. It provides port numbers to help distinguish different user requests and, optionally, a checksum capability to verify that the data arrived intact.

  • TCP has emerged as the dominant protocol used for the bulk of internet connectivity due to its ability to break large data sets into individual packets, check for and resend lost packets, and reassemble packets in the correct sequence. In contrast, UDP just sends the packets, which means that it has much lower bandwidth overhead and latency. With UDP, packets may take different paths between sender and receiver and, as a result, some packets may be lost or received out of order.

  • With TCP, the additional services come at a cost in terms of additional data overhead and delays called latency.

  • UDP can be used for transaction-based protocols, such as DNS or Network Time Protocol.

  • UDP can be used where a large number of clients are connected and where real-time error correction isn't necessary, such as gaming, voice or video conferencing, and streaming media.

  • The User Datagram Protocol header has four fields, each of which is 2 bytes.

  • UDP is known as a "stateless" protocol, meaning it doesn't acknowledge that the packets being sent have been received. For this reason, the UDP protocol is typically used for streaming media. On the other side, TCP is suited for applications that require high reliability, and transmission time is relatively less critical.

  • TCP is a connection-oriented protocol. And UDP is a connectionless protocol.

  • TCP used by HTTP, HTTPs, FTP, SMTP, Telnet protocol. And UDP used by DNS, DHCP, TFTP, SNMP, RIP, VOIP protocol.

  • TCP rearranges data packets in the order specified. In contrast, UDP has no inherent order as all packets are independent of each other.

  • The speed for TCP is slower than UDP.

  • UDP is faster because error recovery is not attempted. It is a "best effort" protocol.

  • UDP Header size is 8 bytes. On the other hand, the TCP header size is 20 bytes.

  • TCP is heavy-weight. But, UDP is lightweight; there is no ordering of messages, no tracking connections, etc. It is a small transport layer designed on top of IP.

  • UDP does not have an option for flow control. In contrast, TCP does Flow Control. TCP requires three packets to set up a socket connection before any user data can be sent.

  • TCP does error checking and error recovery. But, in UDP, Error recovery is not attempted.


Both TCP and UDP have their advantages and disadvantages. UDP is faster, simpler and efficient and hence generally used for sending audio, video files. And TCP, on the other hand, is robust, reliable and guarantees the delivery of packets in the same order. Both TCP and UDP are essential for data transmission.

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