It is not uncommon to find cracks in plaster or plasterboard ceilings. It is not uncommon to find cracks in your wooden ceilings, but this article is about plaster or plasterboard walls that have small or large cracks and what causes the cracks and how to fix them. Believe it or not, most cracks in your ceilings and walls, on any interior drywall or plaster, are going to be a direct result of the structural movement in the house. It could be a small earthquake, the components of the frame begin to shrink, because the wood begins to dry or it can even be the settling of your house. Larger cracks can mean problems with your foundation or even your soil.
If you have a big crack in your ceiling, and you could stick to a quarter, you could have a structural problem and I would recommend contacting a repair contractor in your area to assess your situation.
You realize that you have cracks in your ceilings and that they are not very big, how do you fix them. The easiest way would be to apply a caulk to paint in the cracks and repaint the area. This could save you some frustration in the future, especially if the crack starts to get bigger.
The best way to repair the crack would be to apply fiberglass drywall tape and then apply a standard drywall joint compound to finish the ceiling properly. If your ceiling has an acoustic or wall texture, you will need to reapply to finish on these areas to properly match the existing ceiling.
If you have tiny cracks, I would not even worry about them unless they get bigger. However, you can still apply some caulking and repaint them.
I would like to remind you of something I have already said in this article, if the cracks are larger than the width of a quarter, you might want to contact a building professional. You could have serious structural damage in your foundation or structure.