SimCash
SimCash is the premium currency in SimCity BuildIt. When first starting SimCity BuildIt you start with 50 SimCash. You can acquire more from City Achievements, the Mayor's Pass, Video Ads, Contest of Mayors, Event Tracks, Design Challenges, claiming the golden chest once a week, Club Wars, and purchasing it for real money. Contest of Mayors is by far the best way to earn large amounts of SimCash.
SimCash can be used for many things such as buying buildings that cost SimCash, instantly produce many things, purchase all kinds of currency except platinum keys, add slots to commercial buildings, delete an item from the Trade Depot, NeoMall refreshes, add slots to the trade depot, purchase disaster cards, and instantly finish things that take time like residential zone refreshes.