Write once, run anywhere (WORA), or sometimeswrite once, run everywhere (WORE), is a 1995[1] slogan fromSun Microsystems to describe thecross-platform benefits of theJava programming language.[2][3] It refers to how compiledbytecode from Javasource code can run on anysystem with a compatibleJava virtual machine (JVM). In reality, there can be subtle differences in how a program executes due to variability in JVM implementation and hostoperating system which lead to the comical slogan:Write once,debug everywhere.[4]
As Java has achieved popularity, the installation of a JVM on chips, devices, and software packages became an industry standard practice.
Java's write-once-run-everywhere capability along with its easy accessibility have propelled the software and Internet communities to embrace it as the de facto standard for writing applications for complex networks
So far, the "Write-once, run-everywhere" promise of Java hasn't come true. The bulk of a Java application will migrate between most Java implementations, but taking advantage of a VM-specific feature causes porting problems.