TCP vs UDP

I will be explaining the significant differences between TCP and UDP, and trust me, these differences will tell you why we use TCP rather than UDP for almost all use cases.

1. TCP is a communication protocol through which data packets are transmitted over a network. It includes error-checking, guarantees the delivery, and preserves the order of the data packets. UDP is the same as TCP, except this doesn’t have error-checking and does not ensure or maintain the data packets’ order. For example, you are sending a message to your friend on a new chatting platform. Imagine you are sending a statement: “Good morning Jake.” In the case of the TCP protocol, the message sent to your friend would be “Good morning Jake,” but in the case of UDP, the message may be sent as “Morning Jake Good” (a lot of combinations).
2. TCP is a connection-oriented protocol, but UDP is a connection-less protocol. What does this mean? It means TCP does not send the data when there is no connection with the server. Imagine a lot of users are sending data on the server at the same time. The network is congested, and the server cannot take the load. In TCP, if a connection is made to the server (usually the server accepts the connection), the data is sent. In UDP, no connection is required, which means if the server is too congested, it will receive data through the UDP protocol. Gosh, UDP seems ruthless in these cases, and yes, it is brutal.
3. The data packets transferred in TCP are in sequence that I explained in the first point. The data packets in UDP are not in sequence, and the application layer of the OSI needs to handle the sequence of the data packets.
4. TCP is much more reliable than UDP since TCP provides error checking support and guarantees data delivery to the destination. In contrast, UDP provides only fundamental error checking support.

How TCP works (Image Source)

How UDP works (Image Source)

1. TCP is slower than UDP.
2. Retransmission of data packets is possible in TCP in case packets get lost (technical term: Packet loss). At the same time, UDP doesn’t take care of packet loss.

It is pretty much clear why TCP is better than UDP, but it depends on your application. If you require something like UDP, which is much faster than TCP, you can use UDP.

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