As I get older, I recognise that there is some very old clothing in my closet. Surely nothing from High School, but certainly a few decades old.
A new trick I've been doing with my recent purchases is to take a permanent marker, and write the date you bought the clothing item on an inside tag. This way, you can determine how old the fashion is, and also figure durability of the manufacture and wear and tear. You can see in my photo below where I recently dated a new pair of jeans back in September of this year. As jeans tend to last a long time (I find my waist changes more often than my jeans) this will also inform me of how long I tend to wear/hold clothing.
You can use this trick this week with all your new Holiday Gifts, too!