Can anyone please tell me what's this Ferber method of sleep training? Is it effective?

The Ferber method is a method also known as "graduated extinction". In other words, this method means you'll have to let your baby "cry it out" to get some shuteye. The aforementioned list of when and for whom it's appropriate is accurate based on my research. You should really do the deeper research on this because there are so many specifics that can determine whether or not the method is appropriate for your child. Check out some of these sources to get you started. http://www.babycenter.com/0_the-ferber-method-demystified_7755.bc http://www.parenting.com/article/the-truth-about-ferberizing https://ph.theasianparent.com/new-research-cry-it-out-is-the-best-sleep-training-method/