Comic art has seen countless styles throughout the decades. Some adhere to standard practices, like shading. Artists like Georges Prosper Remi, known by the pen name of Herge, stepped outside of typical comic art techniques and developed a style that has affected comic art to this day; ligne claire, also known as the clear line. This style was created in The Adventures of Tintin.
As the the translation implies, ligne claire is a style that uses strong and consistent clear lines throughout, with little shading. This created images that were deliberately flat, but not simple. This style actually stood out for how much detail it could preserve regardless of action and motion. In contrast, the Marcinelle school of art - seen in works like Asterix - would place emphasis on motion and impact. In addition to the clear line and detailed art, Tintin comics were famous for their realist worlds.
Tintin's adventures incorporated realistic backgrounds and objects based on real world cars, people, and locations. Starting with The Blue Lotus, Herge dedicated himself researching the settings for the books. The characters remained cartoonish to stand out more amid the scenery, but the worlds were almost photographs of the real objects and places they saw, such as China, Tibet, and even space, the latter of which saw months of research for scientific accuracy.
The style of ligne clare truly emerged when 1946 saw the colored re-release of The Blue Lotus. The addition of color laid the foundation for the rest of the series, creating even more believable settings for Tintin's adventures all around the world in the unique art style of ligne claire. This style has endured to this day and influenced countless Franco-Belgian artists, as well as artists such as Roy Lichtenstein, Keith Haring, and Andy Warhol who followed Tintin's clear line.