The history of the Cosmopolitan is a bit murky. One origin-story involves a bartender named Cheryl Cook who introduced the drink at The Strand in Miami around 1988, when Absolut Citron was introduced. Another tale involves a bartender named Neal Murray, who came up with the drink at the Cork ‘n Cleaver in Minnesota in 1975 (using unflavored vodka), and then brought the drink to San Francisco. Toby Cecchini and Dale DeGroff are often credited with this drink's creation, but both more likely just changed the proportions a bit and slung many of them in New York City. The late 90s and early 00s saw the massive upswing of Cosmopolitan orders, mostly due to several characters in the TV series "Sex and the City" ordering them whenever they could.
Many recipes call for Absolut Citron, or generically, a lemon or citrus-flavored vodka. Having tried the drink with Absolut Citron, I can assure most of you that it is much better with normal vodka. I have yet to try with Stoli Citros, but that might be a better option if you want to make with citrus-flavored vodka. I highly recommend using Lakewood Organic 100% Pure Cranberry Juice if you can, or another unsweetened 100% cranberry juice. If you do, add 1/4oz of simple syrup. Otherwise, the classic ingredient is Ocean Spray Cranberry Juice Cocktail (don't use the 100% Juice one that has grape and apple juice in it). If you don't have Cointreau, you can substitute another 80-proof orange liqueur, but a lower ABV triple sec will likely make this drink too sweet. The garnish I believe was originally a lime, but some prefer an orange (sometimes flamed), or even a lemon. Use what you have or prefer. Lastly, feel free to mess around with the proportion of cranberry and lime, you'll see a massive amount of variation in recipes over the years. All that being said, this is a cocktail that I think has had its time, and it's time to move on.