.bam

Source

BAM is a binary version of SAM format: it contains the same information, but it is in 'machine language' so it can be read faster and is lesser in size. It is compressed in the BGZF format. All integers in BAM are little-endian, regardless of the machine endianness. The whole format is formally described in the following table (values in [] are the default when the corresponding information is not available).