k-mer based indexing offers an alternative approach for tasks like sequence comparison and de novo assembly.

A k-mer is simply a subsequence of length 'k' within a larger biological sequence. K-mer based indexing involves breaking down a genome or a set of genomic reads into all possible k-mers and storing them, often in hash tables or bloom filters, along with their frequencies or locations. While less efficient for exact long-read alignment than BWT, k-mer indices excel in other applications. They are highly effective for rapid sequence comparison without alignment, identifying shared patterns between genomes, estimating genomic diversity, or even in tasks like de novo assembly where a reference genome is unavailable. By focusing on short, fixed-length motifs, k-mer approaches can bypass the complexity of full-length sequence alignment, offering speed and flexibility for specific types of genomic queries.