BCFtools is a software package designed for working with genomic data, specifically focusing on Variant Call Format (VCF) and Binary Call Format (BCF) files. It provides tools for manipulating, filtering, and analyzing variant data, making it essential for researchers in genomics and bioinformatics. The tool is widely used for tasks such as variant calling, annotation, and merging datasets. It supports various operations, including querying specific regions of the genome and converting between file formats. BCFtools is often used in conjunction with other tools in the Genome Analysis Toolkit (GATK) and Samtools ecosystems.