The developmental characteristics of babies are different in each month. Babies learn to roll over within 3 months, can sit and stand from 3 months to 6 months, and can walk holding the railings from 6 months to 12 months, which are analyzed as follows: 1. Within 3 months: babies are not mature within 3 months, but during this period babies will learn to roll over and can hold their head straight for 4 to 5 seconds on their own. 2. 3 months to 6 months: From 3 months to 6 months, babies are developing physically and mentally, they can use eye contact, and some of them start to sit and stand. 3. 6 months to 12 months: From 6 months to 12 months of age, babies can walk forward by holding onto the railings and can speak part of the language in a simple way. Since there are individual differences in each baby, the development of each stage is different and parents need to observe and communicate more.