Elimination communication is a practice done in most non-industrialized contries. Rather than training infants to "eliminate" in a diaper, mothers (and other family and community memmbers, when applicable) rely on patterns, timing, cues and intuition to teach babies more appropriate places to urinate and deficate.
There are many reasons to do EC. A few include:
Every mama and baby pair works out their own routine. Some babies are diapered full time, and mama takes them to use the toliet when they know baby needs to go. Some go diaperless. And other do a mix. Some moms do EC part time. They'll try to consistently take baby to the toliet at specific time throughout the day, while using diapers at other times. If you do decide to use diapers as a back up, it's best to use cloth. That will help baby make the connection between the sensation of urinating and getting wet.
There are some great websites and webgroups out there that talk about EC. A few include: