A comic strip (also known as a strip cartoon) is a sequence of cartoons, arranged in interrelated panels to display brief humor or form a narrative, often serialized, with text in balloons and captions. Traditionally, throughout the 20th and into the 21st century, these have been published in newspapers and magazines, with daily horizontal strips printed in black-and-white in newspapers, while Sunday papers offered longer sequences in special color comics sections. With the advent of the internet, online comic strips began to appear as webcomics.

Most strips are written and drawn by a comics artist, known as a cartoonist. As the word "comic" implies, strips are frequently humorous but may also be dramatic or instructional. Examples of gag-a-day strips are Blondie, Bringing Up Father, Marmaduke, and Pearls Before Swine. In the late 1920s, comic strips expanded from their mirthful origins to feature adventure stories, as seen in Popeye, Captain Easy, Buck Rogers, Tarzan, and Terry and the Pirates. In the 1940s, soap-opera-continuity strips such as Judge Parker and Mary Worth gained popularity. Because "comic" strips are not always funny, cartoonist Will Eisner has suggested that sequential art would be a better genre-neutral name.

Comic strips have appeared inside American magazines such as Liberty and Boys' Life, but also on the front covers, such as the Flossy Frills series on The American Weekly Sunday newspaper supplement. In the UK and the rest of Europe, comic strips are also serialized in comic book magazines, with a strip's story sometimes continuing over three pages.

Storytelling using a sequence of pictures has existed through history. One medieval European example in textile form is the Bayeux Tapestry. Printed examples emerged in 19th-century Germany and in mid 18th-century England, where some of the first satirical or humorous sequential narrative drawings were produced. William Hogarth's 18th-century English caricature include both narrative sequences, such as A Rake's Progress, and single panels.

The Biblia pauperum ("Paupers' Bible"), a tradition of picture Bibles beginning in the Late Middle Ages, sometimes depicted Biblical events with words spoken by the figures in the miniatures written on scrolls coming out of their mouths—which makes them to some extent ancestors of the modern cartoon strips.

In China, with its traditions of block printing and of the incorporation of text with image, experiments with what became lianhuanhua date back to 1884.

The origin of the modern English language comic strip can be traced to the efflorescence of caricature in late 18th century London. English caricaturists such as Richard Newton and George Woodward developed sophisticated caricature styles using strips of expressive comic figures with captions that could be read left to right to cumulative effect, as well as business models for advertising and selling cheap comic illustration on regular subscription.

Other leading British caricaturists produced strips as well; for example James Gillray in Democracy;-or-a Sketch of the Life of Buonaparte. His contemporary Thomas Rowlandson used strips as early as 1784 for example in The Loves of the Fox and the Badger. Rowlandson may also be credited with inventing the first internationally recognized comic strip character: Doctor Syntax whose picaresque journeys through England were told through a series of comic etchings, accompanied by verse. Original published in parts between 1809 and 1811 in Rudolf Ackermann's Poetical Magazine, in book form The Tour of Doctor Syntax in search of the picturesque ran to 9 editions between 1812 and 1819, spun off two sequels, a prequel, numerous pirate imitations and copies including French, German, Danish and translations. His image was available on pottery, textiles wallpaper and other merchandise.