Zulu is simple: It is a free and freely re-distributable binary distribution of OpenJDK for Linux, Windows, and Mac OS. Each binary is tested and certified (literally), which in the Java world is no small thing.<p>For MacOS and Windows, Zulu is the only binary distro of OpenJDK that I am aware of. For Linux (as of this writing), Zulu is the only publicly available binary distro of OpenJDK 8 that actually undergoes TCK testing and Java SE compatibility testing. [RedHat provides 7 and 6 binaries through the IcedTea project, but IcedTea has not yet shipped a Java 8 version].<p>So unless you want to build OpenJDK from source (and test top verify what you built is good), you'll need to get a binary from somewhere. Zulu is that somewhere.<p>To demonstrate the simple value of a tested and certified binary build: The current default Java binary thing you get on docker's official Java runtime image for Java 8 is 8u40 (<a href="https://registry.hub.docker.com/_/java/" rel="nofollow">https://registry.hub.docker.com/_/java/</a>). But 8u40 doesn't actually exist. It is still in development in OpneJDK and won't be released until March 2015. So this thing you pull off a repo is certainly not a tested or released version (likely a top of tree snapshot built from source and just pushed to an experimental repo).<p>For a current list of companies and organizations that are actually able to fully test OpenJDK 8 (or 7, or 6), see the TCK signatories list at: <a href="http://openjdk.java.net/groups/conformance/JckAccess/jck-access.html" rel="nofollow">http://openjdk.java.net/groups/conformance/JckAccess/jck-acc...</a><p><< And yes, I work for Azul. >>