1. Visible Line: A solid line representing edges and boundaries visible in a drawing. 2. Hidden Line: Dashed lines representing edges not visible from the current view. 3. Center Line: Alternating short and long dashes showing the center of circles or symmetrical objects. 4. Phantom Line: Alternating long dash, two short dashes, and then a long dash, used to indicate alternate positions of moving parts. 5. Section Line: Diagonal lines used to indicate where material has been cut away in a section view. 6. Cutting Plane Line: Thick dashed lines that show where a section is cut through a part. 7. Break Line: A line that indicates that a portion of the drawing has been omitted. 8. Dimension Line: A thin line with arrowheads at each end that indicates the direction and extent of a dimension. 9. Extension Line: Lines that extend from the object to show the limits of a dimension. 10. Leader Line: A line with an arrow at one end, used to point to a feature on a drawing. 11. Section Line: Different from a section cut line, these are thin lines used to represent the surfaces of an object in a section view. 12. Symmetry Line: Indicates symmetry in a part, typically a thin line with long and short dashes.