C4

[rdmueller]

Shouldn't we add the C4 approach by simon brown to the building blocks?

C4 = context, containers, components, classes

IMHO, if you are not experienced with the building blocks, this approach is really helpful -
level1 = context
level2 = containers (deployment units like .wars and .jars, filesystems, databases)
level3 = components
level4 = classes

[gernotstarke]

A "mapping" explanation could be helpful...

imho C4 mixes different things (esp. deployment and static code structure), whereas arc42 clearly separates those. The "containers" are something that imho should be treated seperately...

[rdmueller]

that is true - Ievel 2 nearly looks like a deployment diagram.
In some examples, he also adds too much detail for my taste - like port numbers...
But I can't think of a better structuring parameter for level 2...