A line that moves tells you something. The trick is knowing what. Not all movement is equal — some lines move because half the country bet the favorite, some lines move because three sharp shops dropped a million dollars on the underdog. Those two moves look identical on a chart and mean opposite things. This lesson is how to read them.
What the line actually represents
A sportsbook line is two things at once. First, it's the book's estimate of the true probability. Second, it's the book's tool for balancing action — adjusting the price to attract bets on the side that's under-bet, so they collect their vig no matter what.
