Difference between frontend, backend, and middleware in web development

Question

I was wondering if anyone can compare/contrast the differences between frontend, backend, and middleware (\"middle-end\"?) succinctly.

Are there cases where they ove

Answer 1

In terms of networking and security, the Backend is by far the most (should be) secure node.

The middle-end portion, usually being a web server, will be somewhat in the wild and cut off in many respects from a company's network. The middle-end node is usually placed in the DMZ and segmented from the network with firewall settings. Most of the server-side code parsing of web pages is handled on the middle-end web server.

Getting to the backend means going through the middle-end, which has a carefully crafted set of rules allowing/disallowing access to the vital nummies which are stored on the database (backend) server.