Infants/Toddlers are rapidly developing physically, cognitively and socially/emotionally. Of course all milestones are very important and exciting but some specific ones you can keep an eye out for are:
Physically since the first two years there is such a rapid growth period there are many milestones. For example, standing alone can occur anywhere from 9th months to 16 months of age. Very soon (about a month) after they begin to stand alone you can expect a little bit of walking alone as well. Remember that during this period in order for your toddler to master each skill they must practice A LOT. On average, when learning to walk toddlers practice on average six or more hours a day. They also fall about THIRTY-TWO times PER HOUR; so no need to worry if they fall down a few times, they WILL get back up. In addition during these developmental times, your children tend to lean on you for advice/support. If their mother says “no” they tend to avoid trying, if they are given a “go” or “yes” they tend to proceed.
Next up, Cognitive development! During the first two years of your Childs life they will go through many different phases of cognitive development, including language development! Typically around one year, your child will say their first recognizable word. It typically tends to be 
mostly babbling or nonverbal communication before then. (showing and pointing.) By the time of their second birthday you can usually expect your little one to have a vocabulary of up to 250 words. As a parent/caregiver you can help support your child’s language development by engaging in “make believe play”, engaging in frequent conversation with them also reading to them and engaging them in dialog about picture books. The role of the caregiver is very important in language development. In the scholarly article, “Role Of Care Giver Stimulation On Toddler’s Language Development in Day Care” they found the “correlation between role of caregiver in giving stimulation with language development toddler was significant and has strong enough correlation”
Lastly, we have Emotional/Social, the third area of development milestones. After your child starts showing different emotions, like happiness, anger, fear, and sadness they begin to develop attachment. “Attachment is the strong affectionate tie we have with special people in our lives that leads us to experience pleasure and joy when we interact with them.” From about 6 weeks to 8 months your child is developing attachment and begin to respond differently to a familiar caregiver than a stranger. By age two, your child will probably have developed the “clear cut” attachment phase and will display signs of separation anxiety when separated from their trusted caregiver. This is a GOOD thing, if your child doesn’t seem to find comfort with you or doesn’t seem to care when you leave, it could be because they haven’t developed that important bond. These healthy feelings of attachment support all aspects of physiological development.