If we leave our nails too long and don't pay attention to cleaning, we may become a place to hide evil people and shelter evil people. Our nails will hide a lot of sludge, and then because our hands are warm, it may breed bacteria, because we usually save water, which has moisture and temperature. In addition, in this sludge environment, bacteria will breed, and then we can catch some food with our hands or do some other activities. Actually, it's not very beneficial.
To some extent, the size of the crescent on our fingernails can reflect a person's health, because in Chinese medicine, the crescent represents the state of yin and yang in the body, and the greater the Le Yan, the longer the person's balance time. Of course, this is a statement on health preservation, which is not always the case in a person's real body, but I think the bigger the crescent on the finger can really represent a person's mental state and better physical state.
You should always trim your nails. Don't make it too long, because it is easy to breed bacteria, and don't make it too short. If they are too short, it will be inconvenient for us to do some things in life. For example, if we rob things and open boxes, it will be very uncomfortable without nails. Basically, if we pull out our ears, we don't have any nails at all. When our body itches, we feel that we want to touch it but can't touch it. This is the most touching.