This is from the official doc for the discourse platform. Hope it clears some doubts.
There are a few levels users can have
0 (New) → 1 (Basic) → 2 (Member) → 3 (Regular) → 4 (Leader)
Users at trust level 0 cannot…
Summary
- Send private messages to other users
- “Reply as new topic” via Link button (UI removed)
- Flag posts
- Post more than 1 image
- Post any attachments
- Post more than 2 hyperlinks in a post
- Have actual links in the ‘about me’ field of their profile (will be silently and temporarily converted to plain text)
- Mention more than 2 users in a post
They can get to trust level 1 by…
Summary
- entering at least 5 topics
- reading at least 30 posts
- spend a total of 10 minutes reading posts
Users at trust level 1 can…
Summary
- use all core Discourse functions
- Upload images and attachments if enabled
- Edit wiki posts
- Flag posts
- have all new user restrictions removed
They can get to trust level 2 by…
Summary
- visiting at least 15 days, not sequentially
- casting at least 1 like
- receiving at least 1 like
- replying to at least 3 different topics
- entering at least 20 topics
- reading at least 100 posts
- spend a total of 60 minutes reading posts
Users at trust level 2 can…
Summary
- Use the “Invite others to this topic” button for one-click onboarding of new users to participate in topics
- Invite outside users to PMs making a group PM
- Daily like limit increased by 1.5 ×
They can get to trust level 3 by…
Summary
This is time and activity based, unlike the previous levels. In the last 100 days…
- must have visited at least 50% of days
- must have replied to at least 10 different topics
- of topics created in the last 100 days, must have viewed 25% (capped at 500)
- of posts created in the last 100 days, must have read 25% (capped at 20k)
- must have received 20 likes, and given 30 likes.*
- must not have received more than 5 spam or offensive flags (with unique posts and unique users for each, confirmed by a moderator)
- must not have been suspended
- These likes must be across a minimum number of different users (1/5 the number), across a minimum number of different days (1/4 the number). Likes cannot be from PMs.
All of these must be true.
Unlike other trust levels, you can lose trust level 3 status. If you dip below these requirements, whether from flagging or the passage of time, you will be demoted to Member. However, in order to avoid constant promotion/demotion situations, there is a 2-week grace period immediately after gaining Trust Level 3 during which you will not be demoted.
Users at trust level 3 can…
Summary
- recategorize and rename topics
- access a private “frequent flier’s lounge” category only visible to users at trust level 3 and higher
- have all their links followed (we remove automatic nofollow1.1k)
- spam flags cast on TL0 user posts immediately hide the post
- flags cast on TL0 user posts in sufficient diversity will auto-block the user and hide all their posts
- make their own posts wiki (that is, editable by any TL1+ users)
- Daily like limit increased by 2 ×
And then level 4 is the mod level that can only be given by the admins.
Of course this is assuming the forum uses the default values and neither @Emily or @oldgods changed them.
Not sure on the number of likes it is set for each level at the moment.