Earth ponies

Earth ponies are one of several kinds of ponies in the series, along with unicorn ponies and Pegasus ponies.

Development
Earth ponies were the original ponies to be featured in the My Little Pony toy line. According to Lauren Faust, the show's developer, Earth ponies have a special connection to nature, animals, and plants. Though they lack the ability to consciously cast spells like unicorns or to fly and walk on clouds like Pegasi, their connection to nature makes them "just as necessary" as and "perhaps more important" than the other ponies.

Depiction in the series
The Earth ponies' connection to the land and animals manifests in various ways. Chiefly, it's expressed in Hearth's Warming Eve where it's stated in the titular holiday's pageant that food can only be grown by the Earth ponies. The pageant describes the Earth pony tribe's role in the founding of Equestria.

Both Earth ponies from the main cast are connected to farming: Pinkie tells the Cutie Mark Crusaders she used to be a rock farmer in The Cutie Mark Chronicles, and Applejack lives and works on a farm. The Apple family maintains apple orchards in Ponyville and Appleloosa, and many Earth ponies work to plow and sow the fields in Winter Wrap Up. Earth ponies also do most of the manual labor, such as scoring ice and clearing snow. In other episodes, Earth ponies are shown pulling rickshaws, carriages, and even trains, suggesting natural physical ability. In more extreme cases, Earth pony characters are shown accomplishing remarkable physical feats such as pulling entire houses across the landscape or easily breaking through barricades, both of which are shown in Hearts and Hooves Day. Their talent for animal care is less prominently featured, though Applejack drives cattle in Applebuck Season, and keeps pigs in her barn. Fluttershy, a Pegasus pony, is a notable exception, as she has her own special bond to the Earth, and she spends most of her time taking care of animals. Fluttershy was originally conceived by Lauren Faust as an Earth pony, which could explain this exception.

However, not all Earth ponies are farmers. Earth ponies work in a variety of professions, including many prestigious or influential ones: Pinkie and the Cakes are pastry chefs, Hoity Toity is a fashion mogul, Photo Finish is a celebrity and photographer, Sapphire Shores is a pop singer, Filthy Rich is a successful businessman, Octavia Melody is a cellist who has played for at least two formal parties, Cheerilee is a school teacher, "Nurse Redheart" is a nurse, and the spa ponies work at a classy spa.

The two-part third-season premiere introduces Crystal Ponies living in the Crystal Empire: They resemble Earth ponies, but have gradient manes and tails; at the end of the premiere, they become slightly translucent. Princess Cadance and the other visitors to the Crystal Empire also acquire these attributes in The Crystal Empire - Part 2. Later in the episode, they are back to normal, with Rarity remarking that the effect is not permanent.

Residence
Earth ponies are seen all over Equestria. According to Twilight in Winter Wrap Up, they are the founders of Ponyville. This is reaffirmed in Family Appreciation Day, when Granny Smith shares the story with Apple Bloom's class of how she and her family established the first agricultural settlement on land that what would ultimately become Ponyville. Earth ponies make up a majority of the residents of Ponyville, along with Appleloosa, where settler Earth ponies live, and in Manehattan, where high society Earth ponies, such as Applejack's Aunt and Uncle Orange, reside. However, because of Earth Ponies' as well as unicorns' lack of the ability to fly or walk on clouds, Cloudsdale does not regularly host them on most occasions besides one exception in Sonic Rainboom when Twilight employs a spell to temporarily grant them with such abilities.