According to BabyCenter.com:
What's your toddler doing? At 20 months, your child should be able to run, though not as smoothly as he'll be able to later. He may also go up stairs by himself, but he'll most likely need some help on the way down. He can probably kick a ball (yup.. he really likes this activity), too, yet hasn't gotten the hang of jumping or throwing overhand.
He's active in less desirable ways as well. Small children frequently resort to hitting, pushing, biting, tugging, and other frowned-on actions to make themselves feel more important but also to experiment: What happens when I hit Kaitlin? Will the same thing happen when I hit Justin? (he did this to his nursery mate) Don't overreact to your toddler's behavior. If you retaliate by hitting, it teaches that hitting is okay. Calmly make clear that such actions are never acceptable — no matter how intensely he's feeling.
Toddlers are naturally curious about everything — including their genitals (totally agreed). Just as they played with fingers and toes when they were younger, they'll begin to play with their genitals now. It's nothing to worry about — unless it's happening nonstop. When your child touches himself in public, don't make a huge deal about it. Just explain that some things are done only at home in private.
How your life is changing: Your toddler is very attached to you, but of course you can't always be together. When you or another important adult leaves, it can be unsettling for your child, who relies on your presence to feel secure. Ease transitions by letting him know beforehand that you're going to leave, and then don't drag out your exit. Give him a quick kiss, and be off.
Parent Tip: How to Avoid "No" "Instead of telling my son no all the time, which can lead to power struggles, try saying things like, "Let's try eating with our fork," "Let's not play with the lamp cord right now — let's color instead." You'll find that giving your child a way out that facilitates communication and listening really pays off." —Mary