The bigBed format stores annotation items that can either be simple, or a linked collection of exons, much as BED files do. BigBed files are created initially from BED type files, using the UCSC program bedToBigBed. The resulting bigBed files are in an indexed binary format. The main advantage of the bigBed files is that only the portions of the files needed to display a particular region are transferred, so for large data sets bigBed is considerably faster than regular BED files.
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