There are multiple methods for writing shorthand, but most of them involve geometric symbols or alphabetical letters in place of full words. While the primary reason to learn shorthand writing is to take quicker and more efficient notes, it can also help conceal communication because other people are unlikely to be able to read very specific forms of shorthand.
One form of shorthand writing is the Pitman system. It was developed in 1837 by Sir Isaac Pitman and uses geometrical lines with different angles and lengths and with a combination of thinner and thicker lines. The system can replace the entire alphabet and is primarily used in England. Those proficient in the Pitman system can write up to 10 times faster than longhand, but it takes a long time for writers to learn.
Another form of shorthand is the Gregg system, named after John Robert Gregg. Unlike the Pitman system, the Gregg system uses lines of equal thickness and does not require complexities such as diacritical marks or even lined paper. For this reason this shorthand method became popular in America, though it is less comprehensive than the Pitman system and typically requires a person to translate his Gregg system notes into longhand shortly after taking them.