LPT: If you’ve been using the same backpack for a while, wash it. You probably can’t smell it, but others can. Your backpack – especially the straps – will accumulate sweat, dirt, and other muck over the year and can get smelly. You may not be able to smell it though because you’re around it all the time. Most backpacks can be washed with regular laundry detergent, either by hand or in the washing machine. Obviously check what materials yours is made of …