UML is a way to talk about things.  Just having a standard-ish way to draw on whiteboards is pretty helpful, even if the diagrams are super temporary.<p>In practice in most industries, most folks can probably get away with just knowing the ISA&#x2F;HASA type stuff and 1..N, * arrity, etc.  Swimlanes are also somewhat useful as a concept (but so are regular flowcharts).<p>There&#x27;s a whole other ton of UML (see 5&#x2F;7th of Rational Rose around the early 2000s, which is probably gone all deep and crazy now, etc) that is, IMHO, pretty skippable.<p>I&#x27;ve not even seen some of the &quot;stuff you have to know&quot; (ball and socket, etc) used.<p>I do think that designs get better when you can draw them, as when they get hard to draw, it becomes conceptually obvious there may be problems.<p>UML generation code tools running against 1300+ Java classes and making some huge diagram covered up in arrows definitely doesn&#x27;t work too well though :)