Sentence:  There is a sense in which simple interference effects are destroyed when a system's environment becomes correlated with its state. This phenomenon is called <WSD>"decoherence</WSD>". I shall consider three approaches here. According to one, <WSD>decoherence</WSD> alone explains why we get determinate records. According to another, <WSD>decoherence</WSD> helps one to formulate a satisfactory interpretation of Everett by selecting a "globally" preferred basis that makes the right physical facts determinate in each Everett branch. According to a third, <WSD>decoherence</WSD> sects a "locally" preferred basis for each observer that makes the right physical facts determinate "from the perspective of that particular observer". 
Meaning of the word marked with <WSD> tags:  Loss of quantum coherence (phase relation between the quantum states of particles) in a physical system as it interacts with its environment.