The *fasta* format ================== .. _classical-fasta: The *fasta* format is certainly the most widely used sequence file format. This is certainly due to its great simplicity. It was originally created for the Lipman and Pearson `FASTA program`_. OBITools use in more of the classical :ref:`fasta ` format an :ref:`extended version ` of this format where structured data are included in the title line. In *fasta* format a sequence is represented by a title line beginning with a **>** character and the sequences by itself following the :doc:`iupac ` code. The sequence is usually split other severals lines of the same length (expect for the last one) :: >my_sequence this is my pretty sequence ACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGT GTGCTGACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTGTTT AACGACGTTGCAGTACGTTGCAGT This is no special format for the title line excepting that this line should be unique. Usually the first word following the **>** character is considered as the sequence identifier. The end of the title line corresponding to a description of the sequence. Several sequences can be concatenated in a same file. The description of the next sequence is just pasted at the end of the record of the previous one :: >sequence_A this is my first pretty sequence ACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGT GTGCTGACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTGTTT AACGACGTTGCAGTACGTTGCAGT >sequence_B this is my second pretty sequence ACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGT GTGCTGACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTGTTT AACGACGTTGCAGTACGTTGCAGT >sequence_C this is my third pretty sequence ACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGT GTGCTGACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTACGTTGCAGTGTTT AACGACGTTGCAGTACGTTGCAGT .. _`FASTA program`: http://www.ncbi.nlm.nih.gov/pubmed/3162770?dopt=Citation