27 operators, each with what it does, what it does well and what Google's documentation says about its limits. Every limit shows where it comes from.
subject:Restricts the search for a word or phrase to the message's subject line." "Searches for words in that precise order, side by side.( )Groups terms so an operator applies to all of them.+Searches for the word exactly as written, without variants.AROUNDFinds two words separated by at most a given number of words.01.2047-100How Gmail splits numbers: a space or a dash separates them, a dot is a decimal point.label:Finds messages filed under a label.category:Finds messages in an inbox tab (Primary, Promotions, Social...).in:anywherein:archivein:snoozedWidens or narrows the search to Spam and Trash, to the archive or to snoozed messages.is:Finds messages that are important, starred, read, unread or muted.has:userlabelshas:nouserlabelsIsolates the messages you have labeled, or those with none of your labels.has:yellow-starhas:red-banghas:green-checkFinds messages carrying a star or icon of a specific color.