What are some reasons to get your work rejected? I have submitted one of my work in a good journal (impact factor 6) and I got rejection after a few weeks. Though I was pretty sure that I covered all the experiments or stuff they can ask for. The reply mail did not show any cause. They just regretted that they cant publish my work. What can be some reasons behind this?
It would depend on the field obviously but I'll have a go at the most common I see in my area.

Outside the scope of the journal
Has been done before
Incremental - minor value
Value of the work was not clear
Not appropriately supported with experimental results
Badly presented in the context of the discipline
Badly written