The term “sleep training” is terribly misunderstood and misused.
A baby who is sleep trained is a baby that is able to fall asleep entirely on his/her own from a state of being fully awake in his/her own cot or sleeping area. Such a baby is also able to go back to sleep on his/her own every time they wake up in the middle of the night. There is also no rule for any fixed age of when a baby is ready for sleep training. Every baby and every family is different and everyone in the house needs to be ready in order to begin sleep training.
Sleep training ≠ “crying it out” (“CIO”). There are several methods of sleep training and while there is no ‘tear free’ method of sleep training, not all of them involve leaving your baby to cry alone for an infinite amount of time. Sleep training for night sleep is also different from sleep training for naps in terms of methods and effectiveness.
Like with routines, everyone has different preferences and lifestyles and there is no right or wrong sleeping arrangement or routine. However, there are age-appropriate amounts of sleep that a baby should be getting, and sleep training can help ensure a baby gets that.