Java projects, especially when it comes to web or EJB applications, tend to get pretty complex. Setting up such a project is a non-trivial task because of the many conventions you have to follow to make your application deployable. The maven project management tool provides a mechanism to setup a project quickly using its archetype concept.
An archetype is a template which creates a skeleton project for you that already knows which dependencies to download and how to build a deployable package. All you have to do is to adjust the maven configuration file (pom.xml) to your needs and fill in code.
When I wanted to play with Seam, all I had to do was to locate a proper archetype and run the following command (all on one line):
mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=softeu-archetype-seam-simple -DgroupId=de.mafr.seam -DartifactId=Seam-Demo -DremoteRepositories=http://maven.softeu.cz
A directory Seam-Demo is created which contains a skeleton project. You can create a deployable WAR-File from it using mvn package.