Chipmunks are small rodents that look like a red squirrel got drunk on fermented apples and had an orgy with hot mice.
When I lived in upstate New York in the Adirondacks we had lots of them on our acreage. About twenty yards away from the A-frame lurked a centuries-old rock wall. This was a perfect environment for the little rodentia to hang out and reproduce.
Whenever someone went outside or onto the front porch the critters began to squeak, or perhaps more like a loud peep, as a warning that the big slow creatures were stirring again. This is similar to how prairie dogs bark whenever they see people. Only one or two chipmunks will make the cute little noise unless different groups of them can see you.
They're rather adorable little fuzzballs and at times can be hilarious as they try to stand up to you and squeak, unless you get too close to them and then they scatter back into their little holes. Their color is a reddish brown, at least in NY, with spots and/or little stripes on their sides.
Imagine someone took the cartoon characters Alvin & the Chipmunks and shrunk them down to the size of your index finger. Now give them some Napoleon complex issues with their size and triple their voice volume. You want to go and hug one but they have sharp teeth that can leave a nasty gash. These teeth are always growing so they have to gnaw on things to wear them down. They are rodents, after all.
They have lots of predators like hawks and snakes, so they keep in balance by breeding like their cousins, the rabbits. Chipmunks eat seeds and plants when they're not getting eaten themselves.