& - logical AND. For example, "gay & photo". Search will find any URLs that contain both "gay" and "photo".

| - logical OR. For example "gay | photo". It's just the same that "gay photo". Space " " is equal for "|". Search will find any URLs, that contain word "gay" or word "photo".

~ - logical NOT. For example "gay & ~photo". Search will find URLs that contain word "gay" and do not contain word "photo" at the same time. Note that ~ just excludes word from result. Query "~photo" will find nothing!

() - group command to compose more complex queries. For example "(gay | lesbi) & ~photo". Query language is simple (and powerful). Just consider query as common logical expression.