Turn the bottle around or look at the box: the ingredient list, the quantity, a batch code and some indication of durability all sit there together. Each answers a different question, and they are easier to read one at a time.
Function and quantity
A rinse-off cleanser, a moisturiser and a facial oil do different jobs; the descriptor tells you which is which. A quantity such as 50 ml is what the bottle contains. How long it lasts also depends on how much you use and how often, which has its own guide.
The INCI list
Ingredients appear under their INCI names, a shared nomenclature that lets you recognise a substance across products and languages: Aqua for water, Latin botanical names, or terms such as Sodium Hyaluronate. To look one up, the European Commission's CosIng database lists these names.
In the EU, ingredients are listed in descending order of weight at the time they are added. Those below 1% may follow in any order after the rest. So a position on the list cannot give you a percentage, and it does not tell you on its own how the whole formula works.
Asterisks and their legends
An asterisk points to a note beneath that particular list. Brands, and even individual products, use it for different things, so always read the legend next to it. If you have a question about an ingredient, write down its exact name.
Dates, PAO and batch
A cosmetic that keeps for 30 months or less must show a date of minimum durability, with an hourglass symbol or the words “best used before the end of”. If it keeps for longer, that date is not required; instead, where relevant, it shows the PAO: an open-jar symbol with a period such as 12M, which in this example means twelve months after opening. Follow the period stated on your own product.
The batch code identifies the production your bottle comes from. Keep it to hand if you need to ask about a specific product, and don't read its digits as a date unless the pack says so.
The European framework for all of this is Article 19 of the Cosmetics Regulation.
Make one useful note
Write down the day you open each product, on the box or in your phone, and keep the box or a readable photo of the label: name, batch and date are enough. Close it properly, use clean hands and keep it away from heat and direct light, in line with the FDA's general advice on using cosmetics safely and shelf life. To keep this record separate from the rhythm of your ritual, see our guide to four weeks and replenishment.