1. Pew released a new report on social media usage. 53% of U.S. online adults aged 18-29 are now on Instagram, and 56% of adults 65+ are on Facebook. Also interesting: Facebook growth may be flattening, but engagement continues to grow.
2. Which factors impact how teens use social media? danah boyd reminds us, “Teens’ use of social media is significantly shaped by race and class, geography and cultural background.” See also: the plural of anecdote is not data.
3. It may be true that Facebook data know more about you than your own mother. Given sufficient (~300) Likes, an analysis of preferences can reveal personality traits better than even a spouse. Do the data we collect and algorithms analyzing this data need something akin to a code of conduct? Incidents like this one over the holidays suggest that we are entering an era where “algorithmic accountability” will be a trend to watch.
4. Read this thoughtful post on what mobile-first really means. It’s not about cramming content on small screens but a need to design products and services with recognition of “the significance of nearly every person on earth having an Internet communicator with them at every single moment.”
5. The Google Translate app, which already delivers more than one billion translations each day, is rolling out a new release. The best new feature? Point your camera at a sign, and the words show up real-time on the screen in your language of choice.

Weekend fun: A serial entrepreneur had a brilliant idea for a business that ships your enemies glitter. And now he wishes it would all just stop. Related: I spent about 50 hours on planes over the past couple of weeks, and would gleefully ship glitter to passengers who acted like this.

Every Friday, find five, highly subjective pointers to compelling technologies, emerging trends, and interesting ideas that affect how we live and work digitally. Try out the Friday 5 archive, or sign up for a weekly email.