On my person I always carry my phone, wallet, keys, flash drive, pocket knife, headphones and pen.
In my backpack (which is on my 90% of the time) I carry a 1 TB external HDD, battery bank, water bottle, various cables for phones and computers, my laptop, a tablet, and a light rain coat, some band-aids, extra pens, and a binder for all my my class work (I am currently working my B.S. in electrical engineering).