Cricket is a multi-faceted sport with different formats, depending on the standard of play, the desired level of formality, and the time available. One of the main differences is between matches limited by time in which the teams have two innings apiece, and those limited by number of overs in which they have a single innings each. The former, known as first-class cricket if played at the senior level, has a scheduled duration of three to five days (there have been examples of "timeless" matches too); the latter, known as limited overs cricket because each team bowls a limit of typically 50 overs, has a planned duration of one day only. A separate form of limited overs is Twenty20, originally designed so that the whole game could be played in a single evening (3 hours), in which each team has an innings limited to twenty overs. Double innings matches usually have at least six hours of playing time each day, with formal intervals on each day for lunch and tea, and additional brief informal breaks for drinks. There is also a short interval between innings. Limited overs matches often last at least six hours, with similar intervals and breaks, whilst the more streamlined Twenty20 matches are generally completed in under four hours. T10 cricket is a newer version of the game, based on the principles of other limited overs formats, but with only 10 overs per innings, and the total playing time limited to 90 minutes. Local club cricket teams, which consist of amateur players, rarely play matches that last longer than a single day; these may loosely be divided into declaration matches, in which a specified maximum time or number of overs is assigned to the game in total and the teams swap roles only when the batting team is either completely dismissed or declares limited overs matches, in which a specified maximum number of overs is assigned for each team's innings individually. These will vary in length between 30 and 60 overs per side at the weekend and the 20-over format in the evenings. Indoor cricket is a variant of the sport played in sports halls during the winter months. At still lower levels, the rules are often changed simply to make the game playable with limited resources, or to render it more convenient and enjoyable for the participants. Informal variants of the sport can be played almost