NFL odds are set by oddsmakers who analyze multiple factors including team performance, historical matchups, player injuries, weather conditions and betting patterns. They create an initial line which is then adjusted based on how bettors wager, aiming to balance the betting action on both sides of the wager. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.