Gas contracts are divided into long term contracts (over one year but often up to 10-20 years), mid-term contracts (approximately up to five years but can be as short as between one month to one year) and short term contracts or master sales agreements (usually up to 1 month or on a cargo-by-cargo basis for LNG), spot contracts (day of purchase). Traditionally, natural gas contracts were on a long term basis fixing the price, volume and conditions over the term of the contract, thus reducing supply and price risks, but they provided little flexibility to adapt to changing market conditions.