Every baby is unique and they all develop different skills at different rates, some walk faster than others, some speak earlier than others but a delay is when a child does not reach his/her milestones by the upper end of the normal range.  Below is a general guideline of what is expected at each age. If you have concerns about your child's development, speak with your pediatrician.

By the end of 7 months:

• turn head when name is called

• smile back at another person

• respond to sound with sounds

• enjoy social play (such as peek-a-boo)

By the end of 1 year (12 months):

• use simple gestures (waving "bye-bye")

• make sounds such as "ma" and "da"

• imitate actions in their play (clap when you clap)

• respond when told "no"

By the end of 1.5 years (18 months):

• do simple pretend play ("talk" on a toy phone)

• point to interesting objects

• look at object when you point at it and tell them to "look!"

• use several single words unprompted

By the end of 2 years (24 months):

• use 2- to 4-word phrases

• follow simple instructions

• become more interested in other children

• point to object or picture when named

By the end of 3 years (36 months):

• show affection for playmates

• use 4- to 5-word sentences

• imitate adults and playmates (run when other children run)

• play make-believe with dolls, animals, and people ("feed" a teddy bear)

By the end of 4 years (48 months):

• use 5- to 6-word sentences

• follow 3-step commands ("Get dressed. Comb your hair, and wash your face.")

• cooperate with other children

By the end of 5 years (60 months):

• say own name and address

• attempt to please and be like friends

• count out 10 or more objects

• understand the difference in fantasy and reality

Source: Centers for Disease Control and Prevention (CDC)