There may be different worms that are available in this world but there are five characteristics that they all share with each other. The presence of all these characteristics will make it clear to you that you are dealing with worms: They do not have legs; They are all invertebrates; They have bilateral symmetry; They have long and narrow bodies; They have heads and tail ends.
Worms are very effective in breaking down organic matter. They can create natural fertilizers that will improve the condition of your soil. A lot of worms are known to be good for plants. There are some speculations that worms can be eaten and while they are known to be good for the body, other people would rather not try it.