Xah Lee has a nice digest (heh!) of the various cryptography algorithms used on the Web. It's not a detailed technical picture—there are plenty of those available—but, rather, a short explanation of each of the major algorithms and how they fit into the Web security infrastructure.
This post does not cover HTTPS, SSH, or SSL/TLS but Lee is promising to cover those in a subsequent article. If you're confused by crypto jargon and are looking for an explanation of what the terms mean and what role they play, you may find this article useful.