DOMs stands for delayed onset muscle soreness meaning it’s the pain and discomfort you get in your muscles after traaining them. DOMs typically lasts 1-2 days the worst case of DOMs I’ve ever had lasted about three days. Back in the day DOMs was to believed to be a build up of lactic acid in your muscles but that has been debunked by science.
Although build up of lactate can cause some soreness in muscles, DOMs is mostly cause by microsopic tears in your muscles making every movement with than muscle slightly painful.
The benefit of DOMs because it lets you know that your muscles are torn and your body is realing the hormones to repair it and causing it to grow. Repeated muscle breakdown is the key to gaining size.
The bad thing about DOMs is your muscles will be tight and performance will suffer. Lifting with DOMs is not necessarily bad, it’s better to let your muscles fully recover before lifting again. Thats why diet and sleep are so important. If you are constantly getting DOMs then you know you are not getting enough rest, protein, or you need to lighten your work load.
With that said DOMs is not necessarily good or bad you will get sore from time to time but if you can increase your work load gradually without constant soreness you are on the right track. You should not train specifically for DOMs it just happens.