When one needs to type long sequences of letters (such as in base-sequences in genes) or of numbers (such as calculations of transcendental numbers), there's no obvious break points to be found. The package provides a command \seqsplit, which makes its argument splittable anywhere, and then leaves the TeX paragraph-maker to do the splitting.

While the package may obviously be used to typeset DNA sequences, the user may consider the dnaseq as a rather more powerful alternative.