FA is the extension of files specific to systems used in bioinformatics. The data in the FA file is saved in the FASTA format and contains a sequence of nucleic acids and proteins, and each component is represented by a one-character abbreviation (capital letter). This is technically a plain text file. Each sequence of nucleotides and amino acids is preceded by a description that begins with the character ">".

FAs are files used in various programs that allow DNA sequencing. This solution is used, among other things, to establish kinship with the help of genetic data.