As a lead-in to its 15th anniversary tomorrow, Google announced changes to its search platform that expand its "knowledge graph"—that is, its ability to answer your questions directly instead of simply presenting you with links to additional sources.

The changes also aim to allow more natural "conversations" that will make it easier to refine searches, and simpler search through musical artists and songs.

Google also updated its iOS and Android search apps, promising additional changes in the near future.

Filter and Compare

Google's Knowledge Graph has been improved to provide better answers to more complex questions that don't have a simple answer. For starters, it will automatically provide a side-by-side comparison when presented with searches such as "butter vs. olive oil," producing an outline in card form that lines up whichever features Google deems most relevant—in this case, calorie and cholesterol counts.

Comparisons can apparently sometimes return less-than-intuitive results. Over at SearchEngineLand, Matt McGee found that comparing Seattle's Space Needle to the Empire State Building yielded images, the date each opened and the buildings' respective architects and styles—but not their height.

Filters, meanwhile, aim to simplify the process of scanning through topics that are frequently searched on the Web. Search for "impressionist artists," for instance, and Google Search will return a card-based rogues gallery of artists that its search experience associated with Impressionism. That result, though, will now also feature a dropdown filter menu that, in this case, would let you select various other styles—Cubist, Renaissance, Realist and so forth.

The company also improved music search so users can explore artists and play songs directly through Search.

App Updates

Updates to the Android Google Search application allow better "conversation," or voice search. Google will understand when you ask a variety of questions surrounding the same topic, and not only provides links to answers but also provides voice feedback.

In a demo, Google director of product management Tamar Yehoshua did a voice search for pictures of the Eiffel Tower, then followed up with requests such as "How tall is it?" and "When was it built?" to demonstrate Google's ability to understand that "it" still referred to the Eiffel Tower.

Upcoming changes to Google's mobile search apps will introduce what the company calls a "more unified design" that's "optimized for touch," and which will introduce the card-based layout from Google Now to search.

Google also promised an update to its iOS application that will let Google Now push reminder notifications to iGadgets the same way it does now on Android. "So if you tell your Nexus 7, 'OK Google. Remind me to buy olive oil at Safeway,' when you walk into the store with your iPhone, you’ll get a reminder," the company noted in its blog post. 

Under The Hood

The engine driving most of these new features is "Hummingbird," Google's latest iteration of its search-indexing algorithm. 

"Hummingbird makes results even more useful and relevant," said Amit Singhal, Google's SVP of search. "And it affects 90 percent of our searches worldwide."

The update, released last month, is the biggest is the biggest revamp of Google's search infrastructure since Caffeine, released in 2010.