Comparison to IRC
Like IRC, Discord is structured around channels on servers, but unlike IRC a given community (like geohashing) will generally operate their own server, with channels per-topic. Discord, the company that hosts the storage and bandwidth and does the technical operation, rarely becomes involved with moderation. Another difference is that IRC accepts any username whether or not it has been previously registered, and only after joining a server is registration of one or more nicknames possible (through NickServ). Discord, however, requires registration up front, although pseudonyms (both globally and per-server) are fine.
For more information on discord, see the corresponding Wikipedia article.
Geohashers on Discord
There is a geohashing Discord server run by January First-of-May. As of 2022, we have over 60 hashers spread across the timezones - a nice level of chat independent of the time of day.
If you wish to join, the invite code/link is: https://discord.gg/BvRfGat