Use 'extant' when discussing objects or traditions from the past that still exist today. The castle is the only extant structure from that era.
Pro Tip 2/3
Present Existence
'Extant' emphasizes that something is currently in existence, despite what one might assume. Despite the rumors of its extinction, the species is still extant.
Pro Tip 3/3
Contrast with Extinct
Use 'extant' to contrast with 'extinct', especially when referring to species that are still alive. The biologist was excited to find the extant population of the thought-to-be-extinct bird.