by 4 months:
Make cooing noises and enjoy making more and more different noises
5-8 months:
Can hold an object and will lift it up to suck it. At first, babies can hold objects, but are unable to let go.
by 6 months:
Make repetitive noises. Can see across a room.
6-8months
Sit wothout support. If your baby is not sitting unsupported by 9 months, talk to your health visitor/GP.
6-9 months
Start trying to crawl. Some babies crawl backwards b4 they crawl forwards. Some learn to walk without ever crawling. Others are bottom shufflers.
6-10months
Pull themselves upright and stand, holding on to the furniture.
Learn to pass things from hand to hand.
By 7 months:
Turn to your voice across the room, or to very quite noices on either side if not distracted by someting else.
9-11 months:
Learn to let go of things, for example, to drop something or give it to you.
By 10-18 months:
Walk alone.
11-13months:
Feed themsleves "finger foods".
by 12 months:
respond to their own name, say something like "mama" and "dada" to parents.