Miles Prowler, better known as Tails, is the deuteragonist of the Sonic the Hedgehog franchise and the long-time best friend and sidekick of Sonic himself. He is an anthropomorphic two-tailed fox, hence the nickname, who aids Sonic on his adventure, usually to defeat Dr. Eggman. He is able to use his twin tails like helicopter rotor blades to fly and is a gifted mechanic, inventor, and aerial pilot.
Yasushi Yamaguchi, originally the main artist and zone designer for Sega’s Sonic Team, designed and created Tails. In November 1992, Tails debuted with the release of Sonic the Hedgehog 2, acting as the secondary playable character to Sonic. Although at this early stage, he did not possess the ability to fly, as he does now.
By 1995, Sega had published Tails Adventure, a solo outing for the character. In it, Tails is tasked with navigating Cocoa Island and defeating the enemies inhabiting it, all while collecting an array of items to aid in his endeavors.
Yamaguchi originally created Tails with the image of him being five years old, despite his official age ending up being eight. That would make him nearly half Sonic’s age. In most properties, Sonic is either 15 or 16.
According to an initial Google search, which presumably bases the age of Sonic and Tails on real-world time, Sonic would be 36 years old, whereas Tails would be 28. The Sonic the Hedgehog video game franchise only loosely follows a timeline, so the characters don’t age between games. For the sake of continuity, Tails is and always will be eight years old, whereas Sonic has always been 15/16.