Some ads take the form of tiles in your start menu. These are there right after installation if I'm not mistaken, but you can easily remove them. Then there are

Some ads take the form of tiles in your start menu. These are there right after installation if I'm not mistaken, but you can easily remove them. Then there are prompts to "finish setting up Windows" which take you to a screen that offers, among other things, a Microsoft Office trial. Apparently there are also adds in Windows Explorer, but I'm not 100% sure I've ever seen them.