Do we start working in sequences in fasta format or fastq format?

[corburn]

From a bioinformatics standpoint, we usually start working with sequence in fasta format

https://github.com/caporaso-lab/An-Introduction-To-Applied-Bioinformatics/blame/51cdcee6519ffc6ea2741694cd456d68f6868072/book/exercises/multiple-sequence-alignment.md#L8

Why does the book claim we usually start working with sequences in fasta format?

For example, in the Qiime Moving Picture Tutorial do we start working with sequences in fasta format or fastq format?