One way in which we generate a lot of landfill waste is by throwing away clothes. The EPA estimates that each American throws away around 70lbs of clothing and textiles each year. That's a lot of clothes! How many of those clothes really deserve to be sent to a landfill? I'm certainly guilty of buying clothes which I've then either never worn or maybe worn once, yet have owned for years. At some point, my de-cluttering self looks in the closet and decides a bunch of those 'junk clothes' need to go. However, there are many alternatives to just tossing your old clothes in the trash. Some of them might save you money, some of them might make you some money, but they'll all make you feel better about bringing down that 70lb/person average!
Maybe the primary reason clothes end up in the trash is because they've ripped or developed a hole. While it's true that sometimes holes, rips, and snags can only really be fixed by patching, anything knit can be darned! Generally, you can tell if something is knit by whether or not it stretches. If it stretches, you should be able to see little loops around the edge of the hole. Grab a needle, some matching thread, a good show on Netflix, and settle in for some good old darnin.' There are thousands of YouTube videos about darning, but here are two good examples that show the process.
I find that with fine knits, like the sweater pictured below, using a silk thread makes the repair pretty durable and also less visible. If you're darning socks, you'll want to choose a yarn that has some kind of nylon or acrylic for durability.