HMS Victory is the only surviving example of a ship of the line. Where does the name "of the line" come from?
she could be used to form a line of battle
she sailed through regular route
she had a lot of lines in rigging
she shared the same design with several other vessels
The line of battle was a naval tactic in which ships form a line, so each ship can fire its broadside without fear of hitting a friendly ship. As breaking of the line ruined this tactic, only the powerful ships (called "ship of the line") were used.