In today's world of smartphones and other mobile gadgets, it is quite possible that most of your communication will take place over mobile apps rather than more traditional methods such as phone calls, SMS messages, and e-mail. Whether you are adding classmates for virtual study groups, scanning QR codes rather than swapping business cards, or swapping contact information with girls at the bar that you want to meet later, you may find your contact lists bloating. With so many people in your contacts, you may forget where you met them or their significance in your life.
Luckily, many mobile communication apps allow you to take notes about each of your contacts. All that you have to do is open the respective note function in the app that you are using, select your contact, add a few comments, and you will be able to refer to them when you forget who's who. This was especially helpful for me when I found my WeChat list approaching 200 contacts, but I was too buzzed from the night before to remember where I met each contact (or how to pronounce each Chinese character in their name).
If the app that you are using does not allow you to take notes about your contacts, then there are alternative. You can edit the name of your contact and jot a few notes down about them. This name change only appears on your end, so you won't have to worry about offending or alarming your friends unless they get hold of your phone. Your other option would be to save your chat logs and try to get their name and other important information in your chat history.
