chaoninja

Hi everyone, So, my question is embarrassingly novice, as I just started grad school and don't have any publications under my belt. My first question is about order of authorship. I understand that, depending on your field (mine is international health), the order you want your name will depend on what phase in your career you are. I know noobs like me want first or second...but why would more advanced folks, maybe tenured, want last author? It it to show they are advising student? Is it actually helpful in their career, or is it more that they want to see their students succeed? Any help understanding how this works is appreciated (i know it varies by field). The other thing...I was offered to be second author by my advisor on some articles that I was not involved with writing, but he wanted to know if I would like to be involved. This seems too easy to me - what is expected? I'm not really sure how to navigate this situation. The problem is not that I don't want to be on publications (of course I do, that's the point) - I just feel odd contributing so little. Should I suggest to be last author? What is the etiquette here? Thanks, sorry for all the uncertainties!