What does TLS stand for?
TLS stands for Transport Layer Security. Transport Layer Security, the protocol that encrypts and authenticates data in transit, for example in HTTPS. It replaced SSL.
TLS protects data in transit. During the handshake the server proves its identity with a certificate and the two sides agree on keys; after that the traffic is encrypted and protected against tampering. HTTPS is HTTP carried over TLS. The current version is TLS 1.3, defined in RFC 8446. Its predecessor SSL is obsolete and should be disabled.
TLS in practice: an example
When a browser opens a banking site, the server sends its certificate. The browser checks that it is valid, matches the site name and chains to a trusted CA, then both sides derive session keys. Someone on the same Wi-Fi sees that a connection exists but cannot read or change its content.
What TLS is confused with
TLS vs SSL: what is the difference?
SSL is the older protocol that TLS replaced. People still say SSL certificate, but every modern connection uses TLS, and SSL versions are insecure. What SSL stands for
TLS vs HTTPS: what is the difference?
HTTPS is not a separate protocol. It is HTTP sent through a TLS connection.
Which exams cover TLS?
TLS is on the official CompTIA acronym list for one of the four exams covered here.
- Security+ SY0-801: on the acronym list, not tied to one objective.
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. A scan reports that a web server still accepts SSL 3.0. What is the correct action?
- Disable SSL and allow only current TLS versions
- Rename the certificate
- Move the site to port 8080
- Lengthen the session timeout
Show the answer
A. Disable SSL and allow only current TLS versions. SSL versions have known weaknesses. The server should offer only supported TLS versions, ideally 1.2 and 1.3.
2. What does the server's certificate provide during the TLS handshake?
- Compression of the data
- Proof of the server's identity
- The client's password
- A faster connection
Show the answer
B. Proof of the server's identity. The certificate binds the server's public key to its name, so the client knows it is talking to the real site before keys are agreed.
Sources: RFC 8446: The Transport Layer Security (TLS) Protocol Version 1.3; NIST SP 800-52 Rev. 2, Guidelines for TLS Implementations. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 11 November 2026.