TDS is a secure protocol, but in previous versions of SQL Server, encryption could be turned off or not enabled. To meet the standards of mandatory encryption while using SQL Server, an iteration of the TDS protocol was introduced: TDS 8.0.
The TLS handshake now precedes any TDS messages, wrapping the TDS session in TLS to enforce encryption, making TDS 8.0 aligned with HTTPS and other web protocols. This significantly contributes to TDS traffic manageability, as standard network appliances are now able to filter and securely passthrough SQL queries.