Single bonds have a very low energy barrier against twisting. This allows conformations to interconvert rapidly at normal room temperature. You cannot easily isolate these different shapes as separate chemical compounds.
This makes them different from configurational isomers like cis and trans shapes. Those rigid isomers require actual bond breaking to change their structure. In a flexible molecule, some shapes are naturally more stable than others.
Staggered arrangements are generally the most stable conformation for a molecule. They space the atoms out and minimize strain from overlapping electron pairs. Eclipsed arrangements force atoms close together and create much higher energy strain.
Bulky groups attached to the molecule further favor shapes that minimize crowding. Chemists use tools like Newman projections to draw and study these twists. They also draw ring flip diagrams to see how cyclic molecules bend.
This conformational analysis helps predict a molecule’s preferred shape and overall stability. It also explains why some chemicals react faster than others in the lab.