What is the principle of next generation sequencing?

Next-generation sequencing (NGS) follows a fundamental process in which DNA or RNA is first broken into smaller fragments. Then, adapters are added to these fragments and the libraries are sequenced. The resulting sequences are then reassembled to form the complete genomic sequence. In specific, NGS utilizes parallel sequencing of numerous small DNA fragments to identify their sequence. The bases of each fragment are identified by emitted signals. NGS has the capability to rapidly sequence hundreds to thousands of genes or entire genomes within a short timeframe. 

It is important to note that NGS comes in two main approaches: short-read and long-read sequencing. In the short-read approach, the genome undergoes fragmentation into small pieces (typically ranging from 50-300 bases) before the actual sequencing takes place. Long-read sequencing uses individual reads originating from a single molecule that is thousands of nucleotides or longer. This approach utilizes fragments with sizes ranging from 1,000-20,000 bases or more.