Some Non-HTTP Request use simple string (unencrypted) to send information request and it can be much easier for attacker to modify the request (Example: FTP/TELNET). But for certain request are using serialized objects or protobuffs (Encrypted, Example: SSH,FTPS,SFTP).
Data streaming from source to destination gets split up into chunks known as "packets" for more manageable transport. Whenever you send or receive a packet of data, a host of information about that data rides along. This includes information added by the Transmission Control Protocol, or TCP.
TCP's job is to ensure that all data sent in a stream moves from Point A to Point B in correct order and intact. Protocols like TCP tell the destination computer which application should receive said data. TCP in particular sacrifices raw speed to ensure reliability in the data being transmitted. Note that some forms of data transmission such as video streaming, where perfect accuracy matters far less than speed, are better off using different protocols that optimize for speed over accuracy.
Packet transfer, if left to its own devices, will not be completely reliable. That's why TCP uses a technique known as positive acknowledgement with retransmission, requiring the receiving end of a transmission to give a response as to what data has been received. Thanks to this, the sender knows what packets to send next, or perhaps resend, to maintain a flawless stream of data. The bytes sent, therefore, can exactly match the bytes received. No data is altered or lost along the way.
UDP (User Datagram Protocol) is a communications protocol that is primarily used for establishing low-latency and loss-tolerating connections between applications on the internet. It speeds up transmissions by enabling the transfer of data before an agreement is provided by the receiving party. As a result, UDP is beneficial in time-sensitive communications, including voice over Internet Protocol (VoIP), domain name system (DNS) lookup, and video or audio playback. UDP is an alternative to Transmission Control Protocol (TCP).