How it works
A multi-slide door runs several large panels on a track, stacking them to one side or splitting them and stacking to both. A bi-fold hinges the panels together in pairs so they fold back against the jamb like an accordion. Either way the point is the same: open most of the wall, not a doorway inside it.
Where it fits an Inland Empire home
This is what people mean by opening up the back of the house, and it shows up on great rooms and family rooms that face a patio. It costs more than a slider and it asks more of the structure, but it changes how a room gets used in a way a normal door does not.
What to watch for
Taking out that much wall usually means taking out structure, and that calls for an engineered header sized for the span and for the load above it. That is a permit conversation with your city before anything comes out, not a decision to make on the day.
More panels mean more panel to panel seams, and every seam is a seal that has to compress correctly for the whole system to stay tight. Hardware quality and adjustment matter more here than on a two-panel slider. The track and rollers also have to be rated for the weight of glass you are specifying, because that is a lot of panel to keep running true.
Glazing carries more weight here than anywhere else in the house, because the opening is the size of a wall. The Climate Zone 10 numbers are the same, a U-factor at or below 0.30 and a solar heat gain coefficient at or below 0.23 on most jobs, but on a west or south-facing opening a patio cover or a deep overhang is close to required rather than optional.