The update policy

Does Maven always download from remote repositories even if an artifact is already available in the local repository? To answer this question correctly, we need to dig deep into how we define remote repositories in Maven.

Remote repositories can be further divided into three: release, snapshot, and plugin.

A release repository holds artifacts that have a fixed version. An artifact with the given groupId, artifactId, and version tags (GAV coordinates) is the same all the time. The following is an example of a released dependency. If you download this dependency today and then again in a month, both will be the same artifact:

<dependency>
  <groupId>com.googlecode.json-simple</groupId>
  <artifactId>json-simple</artifactId>
  <version>1.1</version>
</dependency>

A snapshot repository holds artifacts that have a special version, which ends with SNAPSHOT. Any artifact that has the SNAPSHOT version can change over time. What you download...