What is an INCI name? INCI stands for International Nomenclature of Cosmetic Ingredients, and it's a system of naming ingredients based on scientific names or Latin or English words. Sometimes you'll see the name of something natural - say, shea butter - with its botanical name (Butyrospermum Parkii (Shea Butter) Fruit). Other times, it's a break down of what's in an ingredient like red 40, propylene glycol, water.
For more information, click on this link for the Wikipedia entry.
When buying ingredients, I cannot stress enough the importance of reading the INCI name of the ingredient if you're in doubt. We find suppliers renaming emulsifiers, preservatives, and surfactants a lot, and if you don't want to end up with three bottles of disodium cocoamphodiacetate (which can be found as Coco SilkyCleanse at the Herbarie, under the INCI name at others), learn the INCI name and check before you buy!
For instance, I have been experimenting with a sample of Ritamulse SCG (an emulsifier), which has an INCI name of glyceryl stearate, cetearyl alcohol, and sodium stearoyl lactylate. I'm running out and I want more because I'm quite liking this emulsifier (plus it's Ecocert, which is a bonus if you're selling products). I can't find it under that name at any supplier, but I can find it at the Herbarie as Natramulse or at Lotioncrafter as Ecomulse. By knowing the INCI name, I'm able to find it quickly and only buy one bag instead of two!
Reading the INCI name can help you interpret what you're buying. If you're looking for lavender hydrosol, you want to buy something like Lavandula Angustifolia (Lavender) Flower Water, Methylparaben, Proplyparaben or Lavandula angustifolia (lavender) flower water - you don't want to buy something like water (and) polysorbate 20 (and) Lavandula angustifolia (lavender) essential oil, because that's just water with essential oil in it and some polysorbate 20 to emulsify it all together.
If you're in doubt about knowing the INCI name of an ingredient, read this post on the Everlasting Flower Absolute from Lush's Afterlife moisturizer. There's a big difference between helichrysum and marsh cudweed!
INCI names are really helpful for North Americans reading blogs from Europe, Europeans reading blogs from North America, Australians reading blogs from anywhere, and so on. If I reference something like Amphosol AS-40, look for an INCI name of C14-16 olefin sulfonate when you're at a suppliers' shop to get this product, not the brand name. Brand names can be quite different in different markets! Not only might you not find Stepan brand surfactants in Europe, but they might not distribute over there under that name or might not distribute at all! Learning the INCI names makes it much easier to translate ingredients from one market to another, and will save you a lot of headaches!
You don't have to memorize the names! Keep a list of the ingredients you want with the INCI name beside it. When you see a surfactant - for instance - that looks interesting, check it against the list to make sure you're not buying a third batch of DLS mild!
Here's my example about the confusion one faces when trying to buy "conditioning emulsifier" if you're interested in learning more about the value of learning INCI names.