Reference

WAR (Java web archive)

A WAR (Web Application Archive) is a ZIP-based package that bundles a Java web application — its code, pages, and configuration — into one file for deployment to a Java application server like Tomcat.

Files & formatsGeneral

WAR (Java web archive)

Also known as: WAR file, .war archive, Java web application archive

ZIP-based package for a Java web application
Deployed to servers like Tomcat or Jetty
Related to JAR, but specific to web apps

A packaged web app

A WAR file collects everything a Java web application needs — compiled classes, libraries, web pages, and configuration — into a single archive. Under the hood it is a ZIP with a defined internal layout.

It is a cousin of the JAR (Java Archive): JAR packages general Java programs and libraries, while WAR specifically packages web applications.

How WAR files are used

You deploy a WAR by dropping it into a Java servlet container or application server (such as Tomcat or Jetty), which unpacks and runs it. Because it is ZIP-based, archive tools can also open one to inspect the contents.

Related terms

Keep reading the reference.

Files & formatsZIP archiveA ZIP archive bundles one or more files into a single compressed .zip file that is smaller and easier to share. Unzipping it creates a second, full-size copy of the contents — so an archive and its extracted files can both take up space at once.General Files & formatsArchive fileAn archive file bundles many files and folders into one container — for example a ZIP, RAR, or 7z. Most archives also compress their contents to save space, but some (like plain TAR) only bundle without shrinking anything.General Storage conceptsCompression (lossy vs lossless)Compression shrinks a file by encoding its data more efficiently. Lossless compression rebuilds the original exactly, while lossy compression permanently discards detail the eye or ear is least likely to notice in exchange for much smaller files.General