These days I read a few articles about Transport Layer Security (TLS) protocol. I found two articles that are good enough to dive into the TLS handshake.
For TLS 1.2 https://tls.ulfheim.net/
For TLS 1.3 https://tls13.ulfheim.net/
These two articles analyze the handshake messages for establishing a secure connection between two endpoints, one for TLS 1.2 and one for TLS 1.3. They checked nearly every byte in the handshake messages and give an explanation of they. So an overview of the handshake flow can be pictured.
TLS and SSL, the predecessor of TLS, were designed to provide security communication between a client and a server. However, SSL was proprietary to Netscape, so the IETF organization standardized a new protocol, named TLS, to replace SSL. While TLS 1.2 was released in 2008, TLS 1.3 was released in 2018 to address some improvement. Although TLS 1.3 is the newest version, TLS 1.2 has not been thoroughly replaced. TLS 1.2 is still greatly used today. It is good to learn both of them.