Maven's assumptions

Maven does both - 'makes assumptions' as well as 'enforces' a lot of standards and good practices for project programming and management at an enterprise-level. It also provides some good features such as resource filtering, though not enabled by default, suggest good programming practice. I wish to list down all of them as they come to my mind from the very obvious to the subtle ones below:

1. Projects would have a standard directory layout relative to project's home directory to place source code, target binaries, test source code, test binaries, resources etc as described in the Introduction to Standard Directory Layout.
2. Projects would adopt unit-testing as a standard practice by including the test-compile and test phases as part of the build lifecycle. Maven even goes a step further by failing a build if the test source does not compile or the unit tests fail in its default build lifecycle.
3. Projects provide a clean directory/folder separation between application source code and the resources required (such as Spring applicationContext files, Hibernate configuration files, log4j properties file etc) and not put everything together in project home folder.
4. Projects need not hardcode application properties inside the configuration resources or source code and instead make use of resource filtering - i.e. a property like jdbc.driverName could be externalized in the /src/main/filters and its value will be substituted wherever it is referenced. Thus any changes to it are localized to one file under /src/main/filters although it can be referenced in several places in configuration and code.
5. Modern-day applications (represented by an aggregate project model / POM in Maven) will be divided into separate modules - app-domain-model, app-DAO, app-business-logic, app-web-modules, app-webservices-modules, app-utils etc - instead of old-school monolithic applications. Maven multi-module projects and the Reactor plugin help achieve this.
6. Projects would need to be built for various platforms (Windows, Unix, Linux etc) and deployment environments (dev, staging, test, production) and builds do differ based on the platform and enviroment needed. Eg. different database servers required for each enviroment thereby a different jdbc.url, jdbc.username, jdbc.password for each environment. Maven Profiles are a great feature that if leveraged well can make the build process seamless across environments.