cool thing I learned: if you’re using HTTPS, the information you send and receive from a server is encrypted, right? But someone who’s just analyzing the traffic can still learn a lot of information about you. They don’t know what you’re asking for and what you’re getting, but they know who you’re talking to and how much data you’re getting back. If you’re filing your taxes, you input information about your income or marital service, and based on that the tax service sends you next questions / forms. The form you get if you click ‘I earn more than 200K’ is a different size from the one you get for ‘I earn less than 50K’, and if someone knowns that you’re communicating with turbotax.com & sees the size of the response, they can know how much you earn.
Or if you’re moving around while getting information from google maps, google maps sends you the next chunk of the map based on your movements. The chunk is compressed, and the size of the compression is variable between location-chunks but is constantish for each location-chunk, and can reveal where you are quite precisely. We shed data like skin cells – it cascades off of us even when we think we’ve covered up. We’re irrepressibly radiant with it.