Offer sheet
An offer sheet is a contract offered to a restricted free agent by a team other than the one for which he played during the prior season. Different leagues have different ways to handle offer sheets.
NHL
In the National Hockey League, an offer sheet is a contract offered to a restricted free agent by a team other than the one for which he played during the prior season. If the player signs the offer sheet, his current team has seven days to match the contract offer and keep the player or else he goes to the team that gave the offer sheet, with compensation going to his first team.
Time period
Restricted (Group 2) NHL free agents can discuss new contracts with other teams beginning on the day after that season's entry draft, which is also the deadline for a team to make a qualifying offer. Discussions must cease if a player accepts a contract from his own team or is confirmed to go into arbitration with his team, be it player- or team-filed.
Compensation
When a player accepts an offer sheet and his team declines to match the value of the contract, his former team is entitled to draft pick compensation in the next upcoming draft or drafts based on the averaged yearly salary of the contract. This averaged annual salary is determined by dividing the total compensation by the lesser of the number of years of the Offer Sheet or five years (the latter clause has potentially come into play with one offer sheet---offered to Shea Weber in the 2012 offseason). These values were originally set for the 2005 offseason to coincide with the new NHL Collective Bargaining Agreement, with percentage increases annually equal to the same percentage increase in the average salaries of all NHL players. The 2005 and 2015 offseason values are as follows: