Emacs allows bookmarking inside buffers so that you can quicky visit those at a later time. And by later time I mean any time later, even if its a new emacs session.

The commands are as follows :

Set bookmark C-X r m <bookmark_name>

View bookmarks in the minibuffer C-X r b <up/down arrow> or C-s to I-search (Sounds familiar?)

View a list of all bookmarks C-X r l

Delete bookmark C-X r l (to view list) and then mark with D and delete with x

As you can see a nice thing with emacs is that a lot of old concepts apply to the newly learned stuff for eg. in this case searching for a bookmark can be related to searching for open buffers and deleting bookmarks is to be done just the way we kill open buffers.

Also, if a bookmark is set, it persists in subsequent sessions as well until its deleted. And to jump to any set bookmark, it doesn't require the buffer to be open.

I never used bookmarks in my previous ide which was eclipse. But here it seems quite useful to me. I personally don't like the open files in previous ide session auto-opening up at startup. I prefer starting with a clean slate. So I can just set a bookmark on the dired buffers of the projects that I am working on currently or just set one before wrapping up day's work so that I can start from there the next day.