What programming languages ​​are useful for interacting with the site?

Question

Programming languages

For a clearer explanation of what I need and what I want to know, I will give an example of a simple program.
I enter a link to a site with pictures into the program code, and when it starts, all the pictures (with a given extension and others) will be downloaded to the computer.
Or that the program would give a response to a message that came by email (with sorting: what came in and what to answer is not worth thinking about yet.)
I mean that these programs exist, but how do they work, and with what help?

Answer 1

These kinds of programs are HTTP clients and they work over HTTP/HTTPS protocols over TCP/IP using normal GET requests .
wget is an example of downloading files from the command line.

Answer 2

The language is not important. There is curl to work with both mail and websites.

Answer 3

All of the above can be implemented in any programming language.