As LesZedCB said, LOB is "Line of Business". In practice, this is where your business-logic resides. edit: CRUD means Create-Read-Update-Delete. It's a basic

As LesZedCB said, LOB is "Line of Business". In practice, this is where your business-logic resides. edit: CRUD means Create-Read-Update-Delete. It's a basic programmer term for a simple application, or those simple parts of it at least. Even something big like Wikipedia, at it's core is a CRUD site. Most things are, with business logic sprinkled in; but some things aren't CRUD at all (eg a video game). For example, if you're a car dealership your LOB CRUD API would handle stuff like submitting new cars, or staffs, or associating a sale of a specific car with a specific salesman or whatever other biz logic you have. This could be in contrast with, say, your Document Storage CRUD API which handles integrations with your document storage (eg storing things on a SharePoint, or Ceph, or S3, etc). LOB has no inherent value with regards to microservice vs. monolith, it's simply another way to refer to the business specific logic. The term LOB is common across business as a whole, whereas "business logic" is generally a phrase used by programmers about programs. https://en.wikipedia.org/wiki/Line_of_business https://en.wikipedia.org/wiki/Line_of_business