Why is Sanger sequencing called the chain termination method?

Sanger sequencing is a DNA sequencing technique that relies on the integration of chain-terminating dideoxynucleotides (ddNTPs) by DNA polymerase in the process of in vitro DNA replication. These unique bases are also known as chain terminators. These nucleotides lack a hydroxyl group at the 3' position, leading to the blocking of polymerization during DNA synthesis and ultimately causing termination of the sequence. Chain-termination PCR works similarly to standard PCR, with a notable distinction: the inclusion of ddNTPs. Thus, Sanger Sequencing is also known as the chain termination method.