In the world of Internet, TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are the basic protocols for network traffic.
TCP is a connection oriented protocol, which means that once the connection has been established, it can be transmitted both ways. TCP will automatically check for errors and guarantee delivery of packets sent.
UDP is a simpler connectionless protocol where error-checking and recovery services are not required which makes it faster since the transmission of data will be continued even if the recipient is unavailable.
The main difference between these two protocols is that UDP tends to be faster, whereas TCP is more reliable.
In terms of Windscribe, you will see that we have a UDP and TCP connection protocol in the preferences of our apps. Both of these are using the OpenVPN protocol, just configured slightly differently. As mentioned above, the UDP protocol on its own will send packets and not verify if they are received. However, this functionality still exists when using the UDP option in Windscribe, it's simply built on top of the UDP protocol as opposed to the TCP protocol where it inherently exists without requiring additional functionality.