1. Watermarks:
- Intricate images embedded within the paper during its manufacturing process.
- Viewed by holding a bill up to a light source, revealing a faint profile or object relating to the bill's denomination.
2. Metallic Ink:
- Special ink containing metal flakes used in specific areas of the currency.
- Changes color when the bill is tilted or viewed from different angles.
3. Microprinting:
- Extremely tiny letters or numbers printed onto the notes, often within seals, borders, or near portraits.
- Requires a magnifying glass to read and offers an additional layer of security.
4. Color-Shifting Ink:
- Specially formulated ink used in specified parts of the design.
- Shifts color between copper and green or copper and black when the bill is tilted.
5. Security Threads:
- Thin, vertical strips embedded into the paper during production.
- Appear partially embedded and partially protruding above the paper's surface, usually near the center of the note.
- Some security threads contain microprinting or other unique markings visible under magnification.
6. Ultraviolet (UV) Features:
- Hidden features on the notes that are only visible under ultraviolet (black) light, such as:
- Fluorescent fibers randomly distributed throughout the paper.
- Bill denomination numbers on the front of the note that glow brightly under UV light.
- A UV strip or pattern on the reverse side of the bill.
7. Magnetic Ink Character Recognition (MICR) Code:
- A series of magnetic ink characters printed along the bottom of the bill, near the Federal Reserve seal.
- Used by banks to automatically process and sort banknotes during high-speed counting operations.
8. Raised Printing:
- Certain design elements, such as the portraits, lettering, and seals on the banknotes, are intentionally raised above the surface.
- Can be felt by touch and can be an indicator of authentic currency.
These markings on paper US money produced by the Bureau of Engraving and Printing contribute to the overall security and authenticity of American banknotes, reducing the likelihood of counterfeiting and ensuring public trust in the currency.