Sector Notes are a very useful and convenient way to keep track of intel. There are basically two ways to add sector notes, one over a warp link, while you are scanning a sector, and one while in a sector, by clicking on the add button for sector notes. You can store any bits of information about a sector that you want with sector notes, from the port prices, to the location in the galaxy, to who owns it and how much sector defense they have, etc.