What is the significance of the "A" throughout the story? Scarlet Letter by Nathiel Hawthorne

THE STORY OF THE
SCARLET LETTER
Condemned to wear a bright red "A" over her breast wherever she went, Hester Prynne had been convicted of adultery by Boston's Puritan leaders because she gave birth to a boy while her husband had been away.
Emerging from the prison house with everyone in the town watching, Hester was led to the town square and walked onto a scaffold with her baby in her arms. There on the scaffold she suffered scorn and public admonishment. One women in the crowd criticized the scarlet letter, the mandatory token of her action, saying that it was much to ornate. A minister…