Ada Lovelace, "the first (computer) programmer," is known for having written a description of English mathematician and engineer Charles Babbage's analytical machine. Babbage himself called her "the Enchantress of Numbers". The U.S. Defense computer language, Ada, is named after her.

Formally known as Augusta Ada King, Countess of Lovelace, Ada was born Augusta Ada Byron on Dec. 10, 1815  in London, England. She was the first legitimate child of poet Lord Byron and Anne Milbanke. When Ada was just one month old, Lady Byron left her husband; the two officially separated and Byron left England shortly thereafter.  Two years later he would father Ada's only recognized sibling, half-sister Allegra Byron, the child of Byron and Claire Clairmont; the child would later die at the age of five. It was rumored, however, that Ada had another half-sister: Elizabeth Medora Leigh, the daughter of Byron's half-sister and, scandalously, perhaps Byron. Despite the taboo possibility (which is said to have been confirmed by Ada's mother), Ada and Medora are said to have had some correspondence and association with one another.

Growing up without the presence of a father, Ada was heavily influenced by mother Anne (Lady Byron), who herself took a keen interest in mathematics. Ada received home instruction in the subject from social reformer William Frend; William King-Noel, Earl of Lovelace and Scottish scientist and polymath Mary Somerville.

Ada's association with teacher Mary Somerville led the young mathematician to make her first associations with Charles Babbage, the man whose teachings would later lead Ada to fame in the mathematics community. The two met in 1833.

William King-Noel (then eighth Baron King and later to be titled Earl of Lovelace), another home tutor, became Ada's husband in 1835. It was at this time that Ada adopted the title she would use formally, The Right Honorable Augusta Ada, Countess of Lovelace. Ada and William would have three children: Byron (in 1836), Annabella (in 1837) and Ralph Gordon (in 1839).

Ada's professional life began in 1843, when she translated The Analytical Engine, by Luigi Menabrea, from its original Italian. She also added to certain notes attached to the paper. These involved the "Bernoulli numbers," later to be called the first computer program by historians. There is some disagreement today as to whether the appended notes were actually written by Charles Babbage. Babbage himself commented at the time that he had "suggested that she (Ada) add some notes" to the memoir and that, though the two had discussed which to add, "the selection was entirely her (Ada's) own".

Ada's and Babbage's friendship would continue in the ensuing years, and some historians theorize that Ada contributed in various ways to Babbage's conception of the "analytical machine," one of the world's first computers. It is unlikely that the two were romantically associated, but rather had a meeting of the minds, as professional colleagues in the then very new science were few.

Ada died at the age of 36 from bleeding induced by physicians, who were called in due to her having developed uterine cancer. She is buried in Hucknall, Nottingham, England.