The default method of keyword-matching in Pay Per Click advertising campaigns. Broad match keyword phrases enable your ad to be displayed whenever someone searches for that phrase, similar phrases, singular or plural forms, misspellings, synonyms, stemmings (such as plumber and plumbing), related searches, and other relevant variations.
Broad match reaches the widest audience. But be careful as you might attract irrelevant traffic Click To Tweet
For more checkout Google’s AdWords help page – https://support.google.com/adwords/answer/2497828?hl=en