Twitter system for creating communities is quite different from Facebook and Google plus communities or groups. You can create community by Twitter Lists and groups, generally small by direct message (DM) groups.

Twitter Lists:

You can create Twitter Lists to create a community or a group of people who you wish to follow in a specific group. You can create lists on various topics and then add members to it.

You can also subscribe to the Twitter lists created by other users. Search for the lists on the topic interests you to join them. Also, you can check lists of individuals by clicking their profile and List tab. You can find lists by clicking their profile and List tab. Checking public lists of popular handles in the niche interests you most can help you find the bigger lists.

You can't add yourself in the list you created on Twitter. But, if you create a twitter list by using Hootsuite, you can add yourself to the list.

You can keep lists public or private. To create List click in following steps: Profile -Lists -> Create List -> List Name -> Description -> Select Public or Private -> Save List -→ Add Members to List.

You can add anybody, whether they follow you or not/ you follow them or not.

Twitter DM group:

For small groups, you can also create a Direct Message group on Twitter. DM group will be private.

You can send links, messages, emojis, images via Twitter DM groups.

Create DM group by these steps: New Message Icon -Add username(s) by @ username -> Send Message.

You or members of DM group can add others in the group. All the members can see messages, edit group name.

As anyone can add a new member in the group, you or all the members can see the messages even if the chat isn't following their handle.

DMs are useful for quick sharing and small groups, unlike Facebook groups which can be used to create large communities.

https://www.quora.com/Does-Twitter-have-groups-or-communities-like-Facebook-or-Google-Plus-If-yes-how-do-I-join-a-group?share=1