What does "parent" mean when uploading images? And what does "bump" mean?

A parent post meant its a post with another post similar to it but with minor adjustments. I.E A colored picture would be a parent to the same picture in greyscale.

A bump in comments means that a picture you comment on will be sent to the top as edited. I.E. If you comment on a picture, it will be displayed first on the comments until another picture is commented on then that will be put first.

So you're simply 'bumping' the picture to the top.

Hope I helped.

Also, use parents when posting multiple pages of a comic. The first page is the parent, and then the remaining pages are the child posts.

Actually, with things such as comics, it's best to use pools instead of parenting.

Parenting is used when images "belong" to each other, such as greyscale versions, re-colours, slight modifications and even when an image is an exact duplicate (so that favourites will be moved to the parent image when a duplicate is deleted).

I see now. Thanks a lot for the insight.