Editing Lempel–Ziv–Welch (section)

===Packing order===
Since the codes emitted typically do not fall on byte boundaries, the encoder and decoder must agree on how codes are packed into bytes.  The two common methods are ''LSB-first'' ("[[least significant bit]] first") and ''MSB-first'' ("[[most significant bit]] first").  In LSB-first packing, the first code is aligned so that the least significant bit of the code falls in the least significant bit of the first stream byte, and if the code has more than 8 bits, the high-order bits left over are aligned with the least significant bits of the next byte; further codes are packed with LSB going into the least significant bit not yet used in the current stream byte, proceeding into further bytes as necessary. MSB-first packing aligns the first code so that its ''most'' significant bit falls in the MSB of the first stream byte, with overflow aligned with the MSB of the next byte; further codes are written with MSB going into the most significant bit not yet used in the current stream byte.

GIF files use LSB-first packing order.  TIFF files and PDF files use MSB-first packing order.