All versions of Minecraft require Java to be installed on your PC to run the game. Traditionally, you needed to download Java from various publishers to ensure you had a compatible version installed.
However, starting with version 5, Extreme Launcher simplifies this process by automatically downloading and installing the necessary version of Java for you. This means you no longer have to manually download Java—the launcher handles it seamlessly.
You can get Java either from Oracle or from someone who builds OpenJDK. For the purpose of Minecraft, they are essentially the same, but Oracle's "OTN" version (Oracle JDK uses "Oracle No-Fee Terms and Conditions" as of Java 17 LTS) requires a PAID license for commercial and production purposes. If you make money from streaming Minecraft or running a Minecraft server (even non-profit), you MUST use OpenJDK unless you want to figure out how to pay.