A few people have recently asked me for a poster/cheat sheet/quick reference of the C4 model that I use for communicating and diagramming software systems. You may have seen an old copy floating around the blog, but I've made a few updates and you can grab the new version from http://static.codingthearchitecture.com/c4.pdf (PDF, A3 size).
Simon is an independent software development consultant specialising in software architecture and the author of Software Architecture for Developers. Simon lives in Jersey and regularly speaks to audiences around the world. You can find Simon on Twitter at @simonbrown and Google+.