On dev.Opera, the man we call “Bovo the bachata boss” just published Responsive Images: Use Cases and Documented Code Snippets to Get You Started. It’s excellent; go and read it. (It isn’t a primer to the whole concept; we have one of those in the works.)
We umm-ed and ah-ed about what order to present the examples – “most likely use-case first” or “simplest to gnarliest syntax” order? We eventually decided the second, because the full syntax can be a bit scary.
But don’t that put you off. Responsive images addresses 4 different use-cases. There are also new constructs like
srcset to wrap your bonce around. So the syntax for addressing all four at once is, at first sight, pretty complex.
But, like the most complex of the 24 English tenses, the Future Passive Perfect Continuous tense*, you’ll probably rarely need it.
And if my dull brain can understand it, yours can.
*I used it once, when complaining about how long a repair shop was taking with my guitar. “By our next gig, it will have been being mended for three weeks!”