I was doing a workshop last weekend and while I was showing my work I discovered that two of the pieces in my portfolio are just... dead links. both pieces were made on commission for organizations that no longer exist, and I was reminded of the fact that if you want something on the internet to last you have to host it yourself.

(this is why I'm a mastodon fan. not that I'm hosting my own account right now, but it's good to know that I could!)

I teach tech and I'm often asked why I don't teach some allegedly time-saving proprietary tool/environment/whatever. the answer is that the risk of that proprietary tool just ceasing to exist are really high, and when that happens, the time I spend developing curricula against the tool goes up in smoke. by contrast, notes I wrote for, e.g., python text processing are just as good today as they were ten years ago. over the long run, I think I save a lot of time by teaching only open source tools.
("only" there should come with an asterisk, I don't make a categorical exclusion, especially when teaching for a narrow audience. but "only open source" is my guiding principle)