BED (file format)

The BED (Browser Extensible Data) format is a text file format used to store genomic regions as coordinates and associated annotations. The data are presented in the form of columns separated by spaces or tabs. This format was developed during the Human Genome Project and then adopted by other sequencing projects. As a result of this increasingly wide use, this format had already become a de facto standard in bioinformatics before a formal specification was written.

One of the advantages of this format is the manipulation of coordinates instead of nucleotide sequences, which optimizes the power and computation time when comparing all or part of genomes. In addition, its simplicity makes it easy to manipulate and read (or parsing) coordinates or annotations using word processing and scripting languages such as Python, Ruby, or Perl or more specialized tools such as BEDTools.

History

The end of the 20th century saw the emergence of the first projects to sequence complete genomes. Among these projects, the Human Genome Project was the most ambitious at the time, aiming to sequence for the first time a genome of several gigabases. This required the sequencing centres to carry out major methodological development in order to automate the processing of sequences and their analyses. Thus, many formats were created, such as FASTQ, GFF, and BED. However, no official specifications were published at the time, which affected some formats such as FASTQ when sequencing projects multiplied at the beginning of the 21st century.