Your first task as a Mayor will be to lay the foundation for Sims to live and work and, as you may know, a city isn’t a city without buildings!

These are the three essential buildings

Residential (Where your sims live)

Factories (Industry) (Where you create resource materials)

Stores (Commercial) (Where you create store materials from resources produced at your factories and other stores)

Lastly, these miscellaneous buildings unlock as you level and serve unique purposes

Miscellaneous (buildings that lie outside your city limits that you can upgrade and use)

Side Note:
Thanks to /u/steinauf85 for creating the original building efficiency list available here. A lot of the information has been pulled and modified from his original spreadsheet with his permission. (THANK YOU VERY MUCH!)