To examine a manuscript or proof for errors in writing or typesetting.
Literally to read for the purpose of detecting errors for later correction. DNA polymerase has 3' to 5' exonuclease activity which is used during polymerization to remove nucleotides it has recently added if they are incorrectly paired, and is a correcting ability to remove errors in replication.
read for errors; "I should proofread my manuscripts"
Reading the text to look specifically for mistakes such as grammatical errors, spelling errors, punctuation errors, etc. This is often performed on the final draft to catch little errors that were missed in earlier edits.
To check typeset material for spelling, punctuation, and basic document layout (alignment of elements, etc.).
To examine copy or a proof for errors in writing or composition.
To edit a manuscript for spelling and punctuation errors.