Training pants are meant to hold one pee, unlike diapers that are designed to be worn through multiple wets. That is why many families practicing elimination communication prefer to use training pants, even for newborns, because they want to remove a wet or soiled diaper immediately. Training pants are also trimmer and more comfortable for your baby or toddler.
There are different options in training pants to meet changing needs through your EC'ing journey. Some training pants pull-on like underwear, while others have side snaps or velcro. The side-opening trainers are useful for a miss with solids, as they are easier to remove. However the pull-on style are easier to make and therefore sell at a lower price. Older toddlers may prefer them as the side-snaps may remind them of diapers when they want to feel like "a big kid."
Training pants can also be waterproof or non-waterproof. The non-waterproof training pants are an excellent tool for practicing "diaper free observation time" in your EC practice because they allow you immediate awareness that your child has peed and that it is time for you to give your cue sound (e.g. "pssss".) Waterproof training pants are useful for times when your baby is in care of a non-EC'ing caregiver or in a situation where protecting furniture and floors from wetness is needed.