Its mold its when your your walls get moist make sure they don't get bigger it means you have a leak in your roof!
The line where the ceiling meets the wall is called a cornice. A cornice can be set off from the ceiling with the use of cornice trim. The line where the wall meets the floor is called a baseboard.
The piece of wood that goes in between the floor and wall is called a baseboard.
The corner. Where the floor meets a wall. Or the ceiling meets the wall. In the window sill. In a door way.
bird blocks and ridge vent
An edge. A horizontal edge, to be more precise.
crown moulding
Try to position the ceiling vent so that the air washes down the exterior wall and window eliminating hot spots in the room.
The ceiling.
A ceiling partition is a track on the ceiling that may have a metal or wooden wall fitting into it. This divides a room by the ceiling support.
Non-coplanar lines. They could be parallel or skew.For example, consider yourself facing a wall in a cuboid room. Line 1 = where the floor meets the wall in front of you, Line 2 = where the ceiling meets the wall in front of you, Line 3 = where the floor meets the wall behind you. Then Lines 1, 2 and 3 are parallel but not in the same plane.OrLine 4 = where the walls to the left and behind you meet. Lines 1 and 4 are not parallel nor in the same plane: they are skew.
Why would you need to? The wall is holding the ceiling up. A better description of what you want to do would help.
It is possible for smoke from a wood heater or fireplace to attach itself to the wall where the studs are located. Somehow the studs act like a magnet, I have had this happen in three homes previously.