Twitter uses the t.co domain as part of a service to protect users from harmful activity, to provide value for the developer ecosystem, and as a quality signal for surfacing relevant, interesting…
It's high time people stopped kvetching about Wikipedia, which has long been the best encyclopedia available in English, and started figuring out what it portends instead. For one thing, Wikipedia is forcing us to confront the paradox inherent in the idea of learners as "doers, not recipients." If learners are indeed doers and not recipients, from whom are they learning? From one another, it appears; same as it ever was.