Both campus-based and online teacher certification programs are excellent ways to qualify for a teaching career. Some people like to study with others in a classroom setting, whilst others find online learning more convenient for their lifestyle. Many programs are available, ranging from those that prepare you to teach at pre-school to those that specialise in tertiary teaching, and they're available from bachelor's to doctor's levels.
This page gives details of the programs and where they can be found. In particular, it has useful details of how and where to find online teacher training programs. You might like to check the pages on early childhood education, elementary education, secondary education, special education, and TESOL/TEFL for further details.