Minecraft server modding?

I was about to get into Minecraft server modding but it seems like I’m a bit out of touch. Looking at current community of Minecraft server owners it seems like it largely shifted from Bukkit to Spigot. Which is strange to say at least considering Spigot developers are now also updating Bukkit from what I saw.

Guess it makes sense since Spigot was actually Bukkit fork, built on top of Bukkit. That being said I gotta do some reading and exploring before I can start releasing new plugins 🙂