Raw reads are the unprocessed sequence data obtained directly from sequencing instruments during an NGS experiment. Each read is a short sequence of nucleotides generated from DNA or RNA fragments, and typically includes both the nucleotide sequence and a corresponding quality score. These reads often contain sequencing errors, adapter sequences, and other artifacts, making quality control and preprocessing steps essential before downstream analysis. Raw reads are stored in formats such as FASTQ and serve as the starting point for most genomic analyses, including alignment, variant calling, and assembly.