Yupp.. they know everything. How do we browse, what do we browse, what are our likes and dislikes, our peaking interest in something.
But its actually our fault, most of us never read Terms and Conditions prior to signing up and just tap “i agree” to move ahead. I am pretty sure that facebook T&Cs include a clause which says that facebook is authorised to access your browsing history, your phone mic, speaker, contacts, messages and right down to toilet paper brand you use..