Bits

Bits are coins used as currency in Ponyville. They have the appearance of small, round, gold coins with an embossed rim. "Bit" is a colloquial term for certain coins, and it also can refer to the mouthpiece on a horse's bridle.

Applejack's recurring goal in the first season is to make enough bits to replace Granny's hip and fix the roof of her barn, which is why she wants to go to the Grand Galloping Gala with Twilight Sparkle in The Ticket Master, where she plans to sell her apple treats to make money. In The Best Night Ever, she opens up an apple treat stand at the Gala in the hopes of making some bits, but only one pony, Soarin', actually buys anything.

In Call of the Cutie, while attempting to be a successful apple salespony, Apple Bloom first demands bits from a pony browsing the merchandise (asking for "cash or credit"), then puts apples in Bon Bon's bag without her permission and demands bits from her.

In The Last Roundup, Applejack offers her prize money from the rodeo in Canterlot. The Mayor presses her about it before she leaves on the train.

In The Super Speedy Cider Squeezy 6000 ponies use bits to buy cider from the Apple family. In this episode cents are also mentioned, implying there is a smaller denomination of bits.

Bits' monetary symbols seem to be those of American dollars and cents; both Filthy and Stinking Rich have these as their cutie marks respectively, as well as one of the paparazzi ponies.

Pinkie Pie is seen arguing over the proper price of a tomato in Putting Your Hoof Down, and the price varies between one bit and two. Fluttershy is also seen arguing over the price of a cherry in the same episode, and the price varies between 10 bits, 11 bits, 12 bits, and 20 bits, before finally being sold to another pony for 2 bits.