Born in Geneva, he laid the foundation for many developments in linguistics in the 20th century. He perceived linguistics as a branch of a general science of signs he proposed to call semiology.
His work Cours de linguistique générale was published posthumously in 1916 by Charles Bally and Albert Sechehaye based on lecture notes. This became a seminal linguistics work, perhaps the seminal structuralist linguistics work, in the 20th century.
De Saussure emphasized a synchronic view of linguistics in contrast to the diachronic (historical study) view of the 19th century. (For more on historical study of language, see Philology.) The synchronic view looks at the structure of language as a functioning system at a given point of time. This distinction was a breakthrough and became generally accepted. (For further consideration of the importance of history in the study of language, see Linguistics.)
"A sign is the basic unit of langue (a given language at a given time). Every langue is a complete system of signs. Parole (the speech of an individual) is an external manifestation of langue."
Another important distinction is that between syntactic relations, which take place in a given text, and paradigmatic relations.
De Saussure made an important discovery in Indo-European philology which is now known as the laryngeal theory.
See Structuralism.