I am learning scheme(dr racket), which is i think derived from lisp, what is this actually used for and do people build anything with lisp???

Yes, people do build anything with Lisp, that is why there are at least two commercial Common Lisp systems around, LispWorks and Allegro Common Lisp.

Google Flights is an acquisition of a company using Lisp, ITA Software, they even have a Lisp guide.

https://google.github.io/styleguide/lispguide.xml

In Portugal, Siscog used to be a Lisp shop, no idea nowadays.

Then you have the Clojure based companies, where Datomic and Nubank are two well known ones, even if not a proper Lisp, still belongs to the same linage.

Well, besides pgloader, which achieved a 20~30x speedup via a rewrite from Python to Common Lisp (<https://tapoueh.org/blog/2014/05/why-is-pgloader-so-much-fas...>), there is also this little organisation called NASA which has a collection of theorem proving libraries called variously PVSLib or NASALib (<https://github.com/nasa/pvslib>).

There is a lot more as well, of course, but these two are clear examples of Common Lisp being used in 'the real world'.

This very website that you are using right now, Hacker News, runs on sbcl.

Thanks everyone for opening my mind, actually it is being taught in a core course at my college, and it is very different course form others that i have taken. course teaches feature of lisp how they are unique and useful. Also we are solving simple questions like Fibonacci, or number patterns, list pattern, recursion vs iterative etc.

*I am learning scheme(dr racket), which is i think derived from lisp*

it _is_ Lisp. Namely lisp-1, vs what one would consider lisp like common lisp would be lisp-2. Difference mostly being that in lisp-1 everything's in single namespace, whereas lisp-2 has more. So, in scheme you cannot have a function and a variable have the same name. In common lisp you can. Other diffs being (syntactically) passing functions and executing them. There are other things, of course, but not that big of a deal. Scheme is simpler and suitable for teaching / getting into lispen. I'd argue it might also be a rather well-equipped DSL.

Examples with screenshots: http://lisp-screenshots.org/

Some companies: https://github.com/azzamsa/awesome-lisp-companies/ (Routific, Google's ITA Software, SISCOG running resource planning in transportation, trading, big data analysis, cloud-to-cloud services, open-source tools (pgloader, re-written from Python), games (Kandria, on Steam and GOG, runs on the Switch), music composition software and apps…

More success stories: https://www.lispworks.com/success-stories/

I myself run web-apps and scripts for clients. Didn't ditch Django yet but working on that.

Scheme is mostly used for teaching, but there are many production applications out there written in Lisp (Emacs for example). Also I'd like to mention Clojure, which is "lispy" and used by big cooperations.

Lisp languages are niche, but frequently used as seen in the great projects mentioned in this thread. Since 1982, I have been employed about 20% of my time using mostly Common Lisp and for a few years Clojure. Racket is a great language and system for learning and having fun, so, have fun!

Often as a DSL (domain specific language) for extending applications at runtime and/or configuration. I wouldn't start a "serious" project in Lisp today; meaning, a project with investment behind it, but Lisp can be a real joy to work with, and I've used Clojure for countless hobby projects. Clojure, in particular, has lots of deployments around the tech industry, and it's the foundation of the Jepsen DB test suite, Datomic (an immutable DB), and Metabase, as a few examples. Walmart has a non-trivial amount of Clojure running in prod as well.

I used a few different lisps for pet projects and honestly today for me the biggest problem of lisps is the typing. ADTs (and similar systems) are just super helpful when it comes to long term development, multiple people working on code, big projects or projects with multiple pieces (like frontend+backend) and it helps AI tools as well.

And this in not something lisps explored much (is there anything at all apart from Racket/typed dialect?), probably due to their dynamic nature. And this is why I dropped lisps in favour of Rust and Typescript.