Without talking about specific engines, I think it is important to feel comfortable with the different types of engines, the benefits each type has, and what they are and aren't good for.
Search engines are critical to getting value on the Internet.
If there wasn't an easy way to find information on the Internet, it would be sheer chaos. Imagine if you didn't have a TV listing for your cable stations, or if there was no way to search for books at the library. Search engines provide a similar guiding capability, the difference being that search engines are typically much more powerful. If you want to find a book at the library, you probably step up to a terminal, type in a couple of words, and hope you find a book on that topic. You can also search by author and a few other criteria.