How Google search works: Google creates an index of the web pages it can find and it returns the most relevant results by evaluating more than 200 quality factors. Google's search results are impartial, they're clearly separated from ads and they're returned in less than half a second.
How Google's search ads work: when you do a Google web search, you see ads only when they're relevant. Ads complement search results by offering useful information, especially for commercial queries. Google's ad system is designed to rank higher the ads that are actually useful.
How Google Apps works: it's an online suite of communication and collaboration tools. All the applications and all your data is stored online, so they're not attached to a specific computer. There's nothing to download or install and you can access your files from almost any computer or mobile device.
Sometimes it's difficult to explain the things you are working on because they're familiar to you and they seem obvious. For example, a common misconception about Google search is that Google actually visits all the web pages every time you perform a web search. Of course, that would be extremely inefficient and you would no longer see the results almost instantly.