These terms can feel confusing the first few times you hear them:
- Direct line means that you are descended from the ancestor through a parent-child relationship, ie. great-great-great-grandchild.
- Collateral line means that you are descended from the ancestor through their sibling, most often through an uncle-niece/nephew relationship.
Whether you are direct line descendant or a collateral line descendant will impact whether or not you can use that ancestor for a lineage society application. The majority of societies require direct descent. The Society of Cincinnati may permit collateral lines but direct lines are preferred. When in doubt, prioritize the ancestors in your direct line in your research for your application.