Foals

Foals are young ponies, depicted at various ages on the show, from babies to teenagers. Exact ages are not specified, but there is a clear distinction between babies, school-age ponies, and adult ponies.

Terminology
Foals on the show are smaller than adult ponies, their heads are proportionately larger, and their limbs are shorter. Unlike previous My Little Pony generations, not all younger ponies are called "baby ponies". Child ponies, such as Apple Bloom or Sweetie Belle, aren't referred to as babies, but rather as "fillies". This is the term for females, with the equivalent male term being "colts", though it has not been used in the show proper. The younger versions of the leading characters are simply referred to as "young" or "fillies". The term "foals" is only used by Night Mare Moon, and in a different context (meaning "fool", most likely as a pun). Twilight and Cheerilee refer to the Cutie Mark Crusaders and their classmates as "my little ponies" in The Show Stoppers and The Return of Harmony Part 1, a term also used by Princess Celestia for the main cast.

Appearance
The difference between baby ponies and young ponies is accented in the episode Call of the Cutie. Schoolteacher Cheerilee shows a picture of herself at a very young age, and later contrasts it with another picture of herself being somewhat older than her students. She is depicted not possessing a cutie mark in the former picture, and remarks that "(her) flank was blank" until she grew older and got her cutie mark when she found her talent as a teacher and to help her students bloom with knowledge.

A very strange-looking baby appears in The Mysterious Mare Do Well. Its eyes are styled differently from the usual pony eyes, and they're much more similar to the bead-like eyes with giant eyelashes of the pets from Hasbro's toy line.

Cutie marks

 * Main article: Cutie marks

A cutie mark, a mainstay of My Little Pony, is a special mark on a pony's flank showing an icon related to their special talent.

During Call of the Cutie, Cheerilee tells her students that no amount of pleading, wishing, or begging will make a cutie mark happen before its time, and that the best thing to do is wait. Different ponies develop different special talents as they mature, and at different times; for instance, Rarity's special skill is design, Fluttershy's caring for animals, Rainbow Dash's flight and Pinkie Pie's party-throwing.

One prominent example of a pony finding her talent is Twilight Sparkle. During a flashback in The Cutie Mark Chronicles, she studies hard at magic and her parents enroll her in Celestia's School for Gifted Unicorns. The sonic rainboom spurs her powerful magic into action, showing that she has enough raw magic ability to turn her parents into foilage and enlarge an infant Spike. Celestia informs Twilight that she's never seen that much raw talent in a unicorn before, and her cutie mark subsequently appears.

Trivia

 * All of the six identified colts on the show have unique character designs, unlike the fillies, stallions, and mares, who almost always share the same body design.