A patent is a government grant to an inventor for an invention. George Washington signed the first patent law on April 10, 1790. The law gave patent holders the sole right to make and sell their invention for 14 years. It prevents other people from copying their invention and making money off it during that time. The Patent Act encourages progress in science by allowing patent holders the right to make a living from their own creativity.

To receive a patent, an invention must be new and contribute something useful. A patent can't be granted to something that has already been invented, but a patent can be granted to improve an already existing invention. Patents can be granted to machines, products, devices and processes. Chemical compounds, food, drugs, and the processes to make these things can also be patented.

Before the Civil War (1861–1865), slavery was legal in the United States. Enslaved people were considered property and couldn't apply for patents. This didn't stop them from creating new inventions. Onesimus, a Massachusetts man enslaved by Puritan leader Cotton Mather, is credited with making a remedy for smallpox that was introduced in 1721. Another enslaved person named Papan created a treatment for skin and sexually transmitted diseases (STDs). It was so effective that the Virginia state legislature freed him from slavery so he could practice medicine.

The following three men are notable African-American inventors of the 18th century. All three men were born free; they were not enslaved. There were many more African-Americans, men and women, enslaved and free, who designed, manufactured, and sold inventions. Most of their stories have been lost to history.

Benjamin Banneker

Benjamin Banneker (1731–1806) was a self-taught mathematician and surveyor. When he was 21, Banneker was shown a pocket watch. He was so fascinated by the watch that its owner lent it to Banneker. He spent time studying pocket watches before deciding to build his own timepiece. A year later, Banneker invented a clock out of wood that struck a gong on the hour and kept time to the second. Banneker's wooden clock kept time for more than 40 years.

In 1792, Banneker completed the first Banneker's Almanac. Almanacs were important books in the 18th century because they told exactly when the sun came up in the morning and set at night. Almanacs also listed tide tables, dates of lunar and solar eclipses, holidays, and phases of the moon. Banneker's Almanac was commonly used by farmers and other residents of Pennsylvania, Delaware, Maryland and Virginia during the 18th and 19th centuries.

Banneker gave a first edition of his almanac to Thomas Jefferson. He called on Jefferson to give black men and women equal rights, and to fight against prejudice that was "so prevalent in the world against those of my complexion ... a race of beings, who have long labored under the abuse and censure of the world." Jefferson replied to Banneker, writing, "nature has given to our black brethren talents equal to those of other colors of man." Slavery was abolished 59 years after Banneker's death.

James Forten

James Forten (1766–1842) was born in Philadelphia, Pennsylvania, and lived there most of his life. He served in the U.S. Navy during the Revolutionary War. Captured and imprisoned by the British, Forten was offered his freedom if he agreed to live in England. Forten replied, "I am here a prisoner for the liberties of my country. I never, never shall prove a traitor to her interests!"

After the war, Forten was apprenticed to a sailmaker. He quickly learned the trade and developed a patent for a device to handle ship sails, which made him a wealthy man. Forten used his money to advocate for women's rights and the abolition of slavery.

George Peake

George Peake (1722–1827) also fought in the Revolutionary War. He was the first African-American to be part of the settlement that eventually became Cleveland, Ohio. At this time, Ohio was a largely unsettled frontier in the western part of the United States.

Peake invented a hand mill for grinding corn. His hand mill was made of two round stones approximately 48 centimeters (19 inches) wide. Peake's invention was easier to use than the traditional mortar and pestle, and ground the corn more smoothly. Although Peake didn't patent his invention, he received credit for it in the November 8, 1858, issue of the newspaper Cleveland Leader.