So far, we have been sending random data back and forth. This is great; this means you can have users interact with each other's devices over the network. Imagine we have an app that has an option that toggles the state of a hologram. If one user toggles the state, we can send a message to the other user so that her hologram does the same.
However, what we have not done yet is share coordinates. If we want to place a hologram in the center of a table, then it would make sense if both users saw that object in the same location.
Of course, this only works if the users are in the same area. If they are remote, then you cannot do this. Remember the remark I made when we talked about loading spatial anchors, this can go wrong if the HoloLens does not recognize the room. The same goes for sharing anchors. You can share your anchors but there is no guarantee...