Google is now 15 years old, and the company is celebrating by smartening up its bread-and-butter technology, search, and adding new features such as comparisons and filters. The new features are part of an advanced search ranking system that Google has been rolling out over the past several months, called "Hummingbird." Hummingbird, a Google spokeswoman said, is designed to make users' search results more useful and relevant, especially when they are asking the search engine long, complex questions.