GitHub desktop: Difference between 'Do not include this file' and 'use the modified file'

Question

I am resolving some merging issues in my project, and I noticed there's some files that don't exist on the branch that I am trying to merge:

If I click on "Resolve", I am presented with 2 options:

1. Do not include this file on (my branch name)
2. Use the modified file from (my main branch)

I want to know the difference between this two options.

Answer 1

'Do not include this file on (my branch name)' will mean that the outcome of the merge will not include the file from your main branch, as it was before.

'Use the modified file from (my main branch)' will mean that the outcome of the merge will include the new file from your main branch.

Which option makes the most sense depends on context:

• Have you renamed or moved the file from main to somewhere else?
  • If so, you likely want to not include it in the merge, as it already exists under a different name
• Has it recently been added to the main branch during development of your branch?
  • If so, then you probably want to include it in the merge, so you properly incorporate all changes from the other branch