By default, it treats your search terms as an entire phrase, and looks for the words next to each other. But we do have an Advanced search mode - so if you have fancier searches in mind, you can turn this on by selecting the "Advanced" radio button beneath the search box, and use multiple terms and advanced search operators. This includes a minus sign (-) to exclude terms, and an asterisk as a wildcard

For example, this search for...

  science nano* -nanomachines

  https://scout.sunlightfoundation.com/search/all/science%20nano*%20-nanomachines/advanced

...will find any results that have "science", anything starting with "nano", but exclude results that contain the word "nanomachines".