tooth + brush = toothbrush
basket + ball = basketball
wall + paper = wallpaper
ear + rings = earrings
birth + day = birthday
play + ground = playground
head + ache = headache
gold + fish = goldfish
foot + ball = football
after + noon = afternoon
air + port = airport
bed + time = bedtime
bed + room = bedroom
news + paper = newspaper
news + stand = newsstand
As you'll notice from the last four examples, a single word can be a part of so many other new words (newspaper, newsstand, bedroom, bedtime). English is an interesting language!
What other compound words can you think of?