Some people call them cold chills and others call them thrills or frisson. You may also call them nerd chills, or the chills you get when you get really embarassed. It is that tingly feeling that is somewhat pleasant and associated with your hair standing on end making goose bumps, technically called piloerection.
It is normally accompanied by a cold sensation; hence the nickname cold chills, and creates a shiver or a shudder at times. The skin often dimples on the back of the neck or spine when frisson hits you. The difference between a shiver and frisson is that a shiver is caused by temperature, menopause, or anxiety.
Frisson, however, is an emotionally triggered response. Music that deeply moves a person, speech, or recollections are sometimes causes of frisson. Goose bumps are another thing. They are also called goose pimples, goose flesh, still bumps, chicken bumps, people humps, and Dasler Bumps.
It is a reflex of mammals experiencing strong emotions like fear, nostalgia, pleasure, awe, admiration, or sexual arousal. It is an involuntary response.