Hi S,
A person is Unconnected if they and the rest of their tree is not connected to the main WikiTree tree-that 68% up there. You can see this easily by scrolling to the bottom of a profile. If it has a blurb about being connected to AJ Jacobs, HRM Queen Elizabeth, Liza Kudrow, and Kevin Bacon, then that profile is connected. If there isn't that blurb, then it isn't, and we need to work on doing so by adding family members via blood relationships and marriage until we can find a point where we connect into existing profiles. There are plenty that are not connected to anyone at all-no parents, siblings, spouses, etc, but most have some family attached to them-they just aren't attached to our main tree.