The most popular programming languages can be broken down into 4 categories: website frontend, web-based application backend, mobile app development and embedded systems. JavaScript, HTML and CSS are the most popular website frontend programming languages. For web-based application backend, JavaScript, Python, PHP, C# and Ruby are the most popular programming languages. JavaScript, Kotlin, Java, C# and Swift are the most popular programming languages used for mobile app development. For embedded systems, popular programming languages are C, C++, Python, Java, Rust, Ada, JavaScript, B+, Go, C#, Lua, Assembly and Forth.