The DMG provides insight: they are divine creations.The DMG states on page 11 (emphasis not mine):Quasi-deities have a divine origin, but they don't hear oranswer prayers, grant spells to clerics, or control aspects ofmortal life. They are still immensely powerful beings, and intheory they could ascend to godhood if they amassed enoughworshipers. Quasi-deities fall into three subcategories:demigods, titans, and vestiges.Titans are the divine creations of deities. They might bebirthed from the union of two deities, manufactured ona divine forge, born from the blood spilled by a god, orotherwise brought about through divine will or substance.Examples for titans (or rather: all that are currently published) are the Empyrean, Kraken, Tarrasque (all MM), Astral Dreadnaught (MToF), Slarkrethel (Storm King's Thunder), Atropal (Tomb of Annihilation) and Juvenile Kraken (Ghosts Of Saltmarsh).I'm not aware of any mechanical implications of being or interacting with a titan, except that you're probably gonna have a bad day if you mess with them. But then again, if you fight gigantic monsters like a Tarrasque, it's kind of on you if you get crushed ^^If your DM allows it, you might also be able to choose titans as your Favored Enemy if you're playing a ranger.
Whatever dangers the world may hold, many have decided to face them together. 911 emergency response sim 2018 latest update. Most of the Beaconed islands have created a coalition of island nations to do whatever they can for their common good. This nation has been dubbed The Empyrean Isles, and considers itself to have the highest authority over all other states within the world.
RAW it wouldn't work, but it's similar to how you can choose two types of humanoids as favored enemies, so - considering the scarcity of titans - it wouldn't be too far-fetched to allow it. Football game today. For example, your DM could allow you to switch out one of the humanoid races against titans, so you could, for example, have Orcs and Titans as your Favored Enemies. The 'titan' tag indicates a creature with divine originsThe Dungeon Master's Guide has a sidebar that briefly explores 'divine ranks' on page 11, which says of titans:Titans are the divine creations of deities. They might be birthed from the union of two deities, manufactured on a divine forge, born from the blood spilled by a god, or otherwise brought about through divine will or substance.So the titan tag simply denotes a creature which was directly created by or from a deity in some way.It seems like this designation doesn't necessarily extend to descendants of such a creature - Rocs, for instance, are described in the MM's text as 'Sky Titans' because of being originally created by the giant gods as servants for giants, but don't have the titan tag in their stat block.