This has been shared in the past, but it seems like the time is right to dust it off again.

Arizona Phil of The Cub Reporter does a great job of documenting the MLB roster rules and recently updated with the new CBA.
https://www.thecubreporter.com/mlb-roster-rules-presented-arizona-phil

below is the table of contents, the Lewis Thorpe discussions lately have relied on DFA and Waiver concepts that the sections below do a great job of laying out the process and what a waiver means and the transactions that go with.

• MLB Reserve List (40-Man Roster)
• MLB Service Time 
• MLB Contracts 
• Article XX-B MLB Free-Agency 
• MLB Rule 5 Draft
• MLB Disaster Plan (Restocking Draft)
• Minor League Options
• Designated for Assignment (DFA)
• Waivers
• Inactive Lists
• Post-Season Roster Eligibility
• Amateur & International Talent Acquisition
• Minor League Contracts & Roster Rules 
• Minor League Free Agency

Basically everything I know about transactions and roster rules, I learned it from The Cub Reporter.

One tip is that there is a lot more information at that site than is contained in its table of contents. You can use Google to search the site for terms (or just adding the words "cub reporter" to your Google search works pretty well too). For example, here's a search of that site for injured list information:

https://www.google.com/search?q=site%3Athecubreporter.com+injured+lists

1 hour ago, Otto von Ballpark said:

Basically everything I know about transactions and roster rules, I learned it from The Cub Reporter.

One tip is that there is a lot more information at that site than is contained in its table of contents. You can use Google to search the site for terms (or just adding the words "cub reporter" to your Google search works pretty well too). For example, here's a search of that site for injured list information:

https://www.google.com/search?q=site%3Athecubreporter.com+injured+lists

Yup, there’s also links to related articles in the footers of the write-ups. You can drill down for days!