Architecture is the high-level design and structure of a software system, encompassing the key components, their relationships, and the principles guiding its evolution. It's the stuff that's important to get right early on, because it's hard to change later - and boy do you feel the pain when you get it wrong!
I was in a design review the other day and the new guy kept going on about how great his architecture was - I had to bite my tongue to keep from laughing out loud!
When the CTO asked me to explain our system's architecture, I just showed her a bunch of boxes and arrows - that seemed to do the trick.
Who Needs an Architect? - Martin Fowler argues that architecture is about the important stuff, and that every development team needs to pay attention to it.
Is Design Dead? - Martin Fowler explains that good architecture and agile development go hand-in-hand, despite some perceptions to the contrary.
Software Architecture Guide - This guide from Fowler's site outlines what good architecture looks like, how teams can create it, and how to cultivate architectural thinking.
Note: the Developer Dictionary is in Beta. Please direct feedback to skye@statsig.com.