Avobenzone is the only chemical UV-protection component with a broad spectrum coverage. It can help to block both UVA I and UVA II rays. It's safe and it is allowed to use at a 3% concentration in the USA and a 5% concentration in the EU countries.
There is one problem: avobenzone loses efficiency when exposed to the sun. If you are outside, it loses 36% of its ability to block UV rays an hour after application. That's why it's recommended to reapply sunscreen every 2 hours.
Octinoxate is an effective sun protector that absorbs UV-B rays mostly. That means it can help to protect the skin from burns and from cancer. It’s also a solvent for other sunscreen components. This helps manufacturers to make products less oily.
Water is a great solvent. It’s neutral and doesn’t provide any strong positive or negative effects. It just helps components to mix better and to transport active components.
Butylene Glycol is a very popular synthetic alcohol. It helps the product to absorb deeper and faster. It is also a solvent for other ingredients. As for the skin benefits, it helps to attract water and helps to make the skin softer.
Unlike many other “Glycols”, it is not harmful and that's why it is used in many products. It was approved by US FDA and US EPA for usage.