During Apple’s big hardware announcement on Wednesday, the company placed a particular emphasis on the vapor chamber in the new iPhone 18 Pro and Pro Max. The glossed-over explanation is that these new vapor chambers can improve performance and reduce heat generation. But how exactly? And what does that mean for the phones you’re planning to buy?How vapor chambers workOn a very simple level, vapor chambers work similarly to liquid cooling in other electronics systems like some desktop PCs or server racks. The goal is to carry heat away from the processor to keep it cool, so it can do more work without overheating. A cooler processor is a more efficient processor, which means it runs better.Except, unlike a PC or server rack, a phone is a tight, compact system. There’s not enough space to heat water and then pump it away to a different location to cool it down. Instead, a vapor chamber is a thin, hollow chamber, typically made of either copper or stainless steel, with a small amount of liquid inside. When the liquid inside heats up, it becomes a gas, which then expands outwards, dispersing the heat throughout the body of your phone, rather than keeping it all close to the processor. As it gets further away from the source of heat, the vapor cools back down and becomes a liquid again.