These are also known as "hair muscles". These are tiny muslces that are attached to the hair shaft. These muscles cause the hair to stand up or be erect. When the Arrector Pili muscles contract due to stress, fear or other nervous conditions, the hair becomes stiff and will actually "stand on end".
Daily Hair Tip
To create retro-look hair waves liberally apply a good setting gel, then use massive clips to hold hair in desired shape. Use gentle hairdryer heat, release clips and enjoy lots of new waves.