Daily fantasy football is a style of playing that differs from the traditional year-long season. FanDuel and DraftKings are the most popular daily fantasy sites, each only slightly different from the other. The goal of these daily leagues is to amass the most amount of points by picking the highest scoring players while still remaining under the salary cap.
A dollar value is given to every player based on how well the website thinks they will do this week against their current opponent. Fantasy players will be given a salary cap so that they cannot just pick all of the highly projected players. With that money, they will select one QB, two RB's, two WR's, a tight end, kicker, and one D/ST. The positions who usually score more points are worth more money. Scoring for daily fantasy works the same as standard scoring leagues.
The two most common strategies are putting all of your eggs in one basket or spreading out the cash. When you rely on only a few, expensive players, the goal would be to find value in the other positions if the minimum salary players you pick up happen to do well. This is a risky strategy however, because a bad game out of one of the stars almost automatically ruins your chances. A safer approach is to select all medium salary players who have potential to break through due to their matchup. Looking for value is the most important strategy in daily fantasy.
There are different types of competitions that can be entered. There are large tournaments in which many people can enter and there are huge payouts, and there are smaller daily leagues that have less prize money but give each entrant a higher chance at success.