Limited supply, fluctuating demand. with more bitcoin being sold, the supply lessens making the price go up.

Media attention, Positive news drives prices up, while negative publicity fosters fear and causes investors to let go of their coins.

Government regulations, Depending on the regulations, they can cause prices to go up or down. For instance, Japan decided to accept cryptocurrency as a form of legal payment back in April 2017, sparking a surge in Bitcoin price.