Our Beauty P.I. series is where Makeup.com editor Alanna delves into the history of various makeup products — where they originated and how they’ve evolved. Next up on the list is the origin and conception of today’s top eyeliner.We’ve heard the story of how mascara came to be and how false lashes originated, but we haven’t yet delved into the one cosmetic that bridges these products together: eyeliner, of course! Unique in formulation, eyeliners are one of the most diverse makeup products on the market — they come in all shapes, sizes, and colors. Originally a practical tool for the ancients and an art tool for makeup artists, these pencils and liquids have taken on many roles throughout the years, eventually morphing into the beloved longwear pencil we use today (thank you, Urban Decay!). Here’s exactly how it went down. The Good “Kohl” DaysThanks to the gorgeous ancient murals of Egypt and Mesopotamia in museums and art history textbooks,you probably know what OG liner looked like. The eyes were considered the windows to the soul, and ancient eyeliner dates back as far as 1070 BC, when old school gurus used kohl to decorate the outer rim of the eye and protect it from the sun. According to Classic Beauty by Gabriella Hernandez, “kohl was commonly made of machalite, galena copper, iron manganese, and lead,” while other ingredients such as burnt cork or soot were also used to darken the eyes. Application wise, our ancient ancestors had it figured out: “Kohl was mixed with oil or fat and applied with a shaped stick,” much like it is today. The Silent Film EraThe use of eyeliner was pretty primitive for the hundreds of years that followed (the women of the Crusades, Marie Antoinette and Queen Liz I were not kohl fans, as they were too busy powdering their faces). Eye makeup focused around mascara up until the 1920s when liner finally began to evolve thanks to theater and silent film. Theda Bara, a renowned silent film actress, was one of the first to popularize the heavily lined eye thanks to Helena Rubinstein’s powdered kohl product. In fact, Cosmetics and Skin reports that there were very distinctive ways to wear eyeliner during this time: “In the European tradition, it [was] more common to line the outside of the eyelashes – above the upper lashes and below the lower ones. In the East, powdered kohl [would] be smudged around the eye, but it is also applied on inner surface of the eyelid — known as the conjunctiva, inner rim or waterline.”The First Commercial Eyeliner is Born In 1929, Maybelline created and marketed their very first eyeliner, which was sold alongside the first eyeshadows and the company’s signature “eyelash darkener,” the OG name for mascara. Maybelline ads featured them as kits: You’d have to buy all three products to achieve the finished look. Eye makeup finally became a multi-step routine. The Development of Liquid Liner and ColorBy the 1950s, eyeliners was a staple in makeup bags far and wide. But a new liner was on the rise: liquid formulas. “New solvents improved the drying time that led to the creation of products like liquid liners,” Classic Beauty reports. And by “the 1950s, Audrey Hepburn’s doe-eyes encouraged women to experiment with looks more than ever.” Less than a decade later, Maybelline came out with their first Fluid Eye Liner as well. In addition to these new formula discoveries, long-lasting color was finally making its way to eyeliner in the 70s, 80s, 90s and beyond. According to Classic Beauty, “gel eyeliners and cream-based shadows that did not smear or flake provided an alternative to pencils and liquids that did so.” Colors also ranged from deep blacks to neutrals, rainbow brights, neons and everything in between — there was no limit.  verdana Style icon.A post shared by Illumina (@illuminasoycandles) on Jul 12, 2018 at 2:13am PDTOur Favorite Liners TodayThis finally brings us to our favorite liners of today, and we have the perfect combination of everything eyeliner has come to be: pigmented, long lasting and available in a rainbow of colors. Cue: Urban Decay 24/7 Glide-On Eye Pencils, in all of their electric shades. “The inspiration for the 24/7 pencils came from an art exhibit I went to at the Orange County Museum of Art,” says Urban Decay Founder and Chief Creative Officer, Wende Zomnir. “It was an exhibit on skate culture and street art — and the colors and textures really inspired me to create the 24/7 pencils in a huge range of colors so that people could use them as tools to express themselves.”Zomnir notes that the name “24/7” of course refers to the pencil lasting 24 hours a day, seven days a week, and she’s totally serious. “I wanted these pencils to be super long-lasting — almost as if you had created a work of art on your face and didn’t want it to go away,” she says. “The whole idea was to create a new and innovative pencil that was waterproof and smudgeproof — these were the first of their kind on the market. You could put them on and once they flashed down, they literally didn’t move.”But what makes the Urban Decay 24/7 pencils different from other eyeliner pencils is that they’re super soft and feel like *almost* nothing, Zomnir adds. “There’s no tugging on your skin; it’s kind of hard to believe that something so creamy and blendable can dry down to such a long lasting finish.” And she’s not wrong — this is one of the most, if not the most comfortable long-wearing eyeliner on the market to this day.  One of our favorite ways to add a pop of color to any makeup look 🌈✔️ 😍Which 24/7 Glide-on Eye Pencil is your go-to? #UrbanDecay #Makeup #BeautyA post shared by Urban Decay Cosmetics (@urbandecaycosmetics) on Jul 11, 2018 at 6:00pm PDTOf course, the 24/7 pencils are also beloved for all the incredible colors they come in, and that’s a major part of the liner’s magic, Zomnir urges. “We decide on new colors for our 24/7 pencils collection in a couple of ways. First, we look at what’s trending on the market and what are the shades people want to wear.” Zomnir also notes that new color is also decided on innovation. “There’s always new pigments and textures we can blend into the 24/7 formula to find new shades. Some of the new metallic pencils we are in the process of developing are a great example of this — they’re super high shine, super metallic, and even a few years ago, this level of metallization wouldn’t have been possible.”But one thing is for certain: the 24/7 pencils embody what eyeliner has always been since its beginning as kohl: a form of expression. “There are so many different ways to use the 24/7 pencils above and beyond,” Zomnir suggests. “They’re like art pencils — you can really have fun with them and use them for creating art on the face.” And that’s something we think our eyeliner-loving ancestors would get behind.