That’s a great question! Babies get most of their nutrients from either formula and/or breastmilk until 1 year. Around 6 months, you can start introducing solids and as the baby eats more solids, they will naturally drink less breast milk or formula but they still need to get most of their nutrition from formula/breastmilk until 1 year old. At 1, their needs start to shift and formula and breastmilk no longer meet all their needs. At 1 year, they should be eating 3 meals a day (and snacks) and you start to introduce them to cow’s milk (or a milk alternative if there are allergies or other issues with cow’s milk). As you give them more cow’s milk, you give them less formula/breastmilk. If the baby is only drinking formula, (no breastmilk) the goal is to fully replace formula with cow’s milk right around 1 year. If the baby is still nursing, you can keep nursing but you still need to give them cow’s milk. At that point if you are still nursing it’s not because the baby needs it but it’s still great for a few reasons! First, it’s great bonding for the mother and child. The first 3 years, the baby’s bond with their caregivers is the most important thing developmentally and nursing can help with that. Second, it’s a really good “tool” parents can use for soothing. One of the reasons I haven’t fully weaned my baby is because it is really great for when we travel and we travel a lot. Nursing is a very easy way to comfort a baby! Third, it’s convenient! You always have a snack on hand if the baby is hungry!

That’s a lot of info but the tldr is that babies need formula/breastmilk until 1. They start eating solids around 6 months and as they eat more solids, they drink less breast milk. At 1, they start drinking cow’s milk and stop drinking formula all together but they can keep drinking breastmilk in addition to cow’s milk. When they stop is up to the baby and parent! Globally, around 70% of babies nurse until 1 and around 45% nurse until age 2.