Technologies for Web Development -- General [on hold]

Technologies for Web Development -- General [on hold]

I am beginning to venture into web development. I am currently a
undergraduate CS major. Up until now, all I have ever learned is Java,
C++, C, HTML, CSS, and MySQL.
In terms of web development, know JavaScript is used for front end, PHP
for back end, but that's it.
My question is, what languages are used to do actual web programming? I
have read a ton on here but I am still a bit confused.
Say for example I wanted to compare 2 facebook profiles, run some data
analytics on the scraped information, and then do something with them?
For this example, I know I would use HTML, CSS, and JavaScript for design
and front end, but what language would I write the logic for the "analytic
engine"?
Or what if I wanted to index a finite universe of facebook profiles and
pick the 2 most similar profiles and display some data on them on a
webpage (and do this once daily)? What language would I use for this?
Thank you very much!