This is a web development site. I teach Git, GitHub, HTML, CSS, JavaScript and many libraries and templates. Also, there are at least 5 websites which explain Blockchain, Cryptocurrencies, and the like. Deep dive per University of California at Berkeley, UC Davis, University of Michigan and the Superstars at Linux. Linux defines the internet & didn't charge for it. The only outfit who did NOT. Sadly, so many (MS) charge for products stolen from the public archives. Languages like C, C++, SQL, Pascal, Fortran, Cobol, Basic, etc. And even operating systems, database management systems (DDL, DML, DCL). These were developed with public funding.