BLAT is a fast and accurate alignment tool for mRNA/DNA and protein sequences, significantly faster than existing tools. It uses a K-mer index of the genome, allowing rapid alignment by searching for matching K-mers in the query sequence. BLAT is optimized for speed and sensitivity, with different K-mer sizes, mismatch schemes, and index match requirements affecting performance. It is compared with other alignment programs on various test sets and used in genome-wide applications. A web-based BLAT server is available for human genome alignments. BLAT is used in three major applications: producing human EST and mRNA alignments, aligning mouse whole-genome reads against the human genome, and powering interactive searches on the UCSC genome website. BLAT can handle nucleotide, protein, and translated nucleotide alignments. It is available in client/server and stand-alone versions, with the client/server version suitable for interactive use and the stand-alone for batch processing. BLAT is efficient for long database sequences but not recommended for queries longer than 200,000 bases. It is more efficient for short queries and does not require DNA masking for untranslated searches. Translated searches benefit from masking to improve results. BLAT's algorithm involves a search stage to identify likely homologous regions and an alignment stage to produce detailed alignments. It uses multiple perfect matches or near-perfect matches to reduce the number of alignments checked, improving speed and sensitivity. BLAT can handle insertions and deletions, and is more sensitive than some other tools for detecting coding regions. BLAT is more accurate and faster than Sim4 and other tools for mRNA/DNA alignments. It is used to align 713 mRNAs back to chromosome 22, showing high agreement with Sanger annotations. BLAT is also effective for translated alignments, aligning mouse reads against the human genome with high sensitivity. BLAT is used for both nucleotide and protein alignments, with different settings for each. It is faster than TBLASTX for vertebrate genome comparisons. BLAT's search stage uses K-mers to identify homologous regions, while the alignment stage extends these into detailed alignments. BLAT is efficient for large-scale genome projects and can handle millions of reads quickly. BLAT is available for non-commercial use and can be obtained for commercial purposes. It is used in various genome projects and is a valuable tool for sequence alignment in genomics. The tool is optimized for speed and accuracy, making it suitable for large-scale genomic analysis.BLAT is a fast and accurate alignment tool for mRNA/DNA and protein sequences, significantly faster than existing tools. It uses a K-mer index of the genome, allowing rapid alignment by searching for matching K-mers in the query sequence. BLAT is optimized for speed and sensitivity, with different K-mer sizes, mismatch schemes, and index match requirements affecting performance. It is compared with other alignment programs on various test sets and used in genome-wide applications. A web-based BLAT server is available for human genome alignments. BLAT is used in three major applications: producing human EST and mRNA alignments, aligning mouse whole-genome reads against the human genome, and powering interactive searches on the UCSC genome website. BLAT can handle nucleotide, protein, and translated nucleotide alignments. It is available in client/server and stand-alone versions, with the client/server version suitable for interactive use and the stand-alone for batch processing. BLAT is efficient for long database sequences but not recommended for queries longer than 200,000 bases. It is more efficient for short queries and does not require DNA masking for untranslated searches. Translated searches benefit from masking to improve results. BLAT's algorithm involves a search stage to identify likely homologous regions and an alignment stage to produce detailed alignments. It uses multiple perfect matches or near-perfect matches to reduce the number of alignments checked, improving speed and sensitivity. BLAT can handle insertions and deletions, and is more sensitive than some other tools for detecting coding regions. BLAT is more accurate and faster than Sim4 and other tools for mRNA/DNA alignments. It is used to align 713 mRNAs back to chromosome 22, showing high agreement with Sanger annotations. BLAT is also effective for translated alignments, aligning mouse reads against the human genome with high sensitivity. BLAT is used for both nucleotide and protein alignments, with different settings for each. It is faster than TBLASTX for vertebrate genome comparisons. BLAT's search stage uses K-mers to identify homologous regions, while the alignment stage extends these into detailed alignments. BLAT is efficient for large-scale genome projects and can handle millions of reads quickly. BLAT is available for non-commercial use and can be obtained for commercial purposes. It is used in various genome projects and is a valuable tool for sequence alignment in genomics. The tool is optimized for speed and accuracy, making it suitable for large-scale genomic analysis.