Comment by nextgens
5 months ago
TLS1.0 introduced modularity via the concept of "extensions". It's everything but a minor evolution of the protocol.
One of the many things it brought is session tickets, enabling server-side session resumption without requiring servers to keep synced-up state. Another is Server Name Indication, enabling servers to use more than one certificate.
FWIW, these aren't actually in TLS 1.0.
Extensions (including SNI) are in later spec but introduces in RFC 3546 (https://www.rfc-editor.org/rfc/rfc3546). Session tickets are in RFC 4507.
What TLS 1.0 did was to leave the door open for extensions by allowing the ClientHello to be longer than what was specified. See https://www.rfc-editor.org/rfc/rfc2246.html#section-7.4.1.2 (scroll to "Forward Compatibility Note")