= Sequencing read
A <sequencing read> is an ordered series of base calls inferred from one sequencing measurement or molecule-associated signal. It is evidence about a <nucleotide sequence>, rather than the original molecule itself. A read can also carry base-quality estimates expressing uncertainty in individual calls. <Talking Glossary of Genomic and Genetic Terms by NHGRI>[DNA Sequencing and Sequence entries]{ref}
For a base-call error probability $p$, a Phred quality score is $Q=-10\log_{10}p$: $Q=20$ corresponds to an estimated error probability of 0.01. A long read with uncertain bases and many short overlapping reads therefore provide different kinds of evidence. Aligning reads, building a consensus and interpreting a <mutation> are further inference steps. Repeated reads need not represent independent starting molecules, especially after amplification.
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