Search Theme is a Performance Max signal that lets advertisers provide topics or queries they know are relevant to customers.
It matters because paid search can spend budget quickly. Knowing this term helps teams control intent, targeting, bidding, creative, conversion tracking, and lead quality instead of optimizing for surface-level clicks.
Example
A tour operator adds search themes such as sunset boat trips and private coastal tours to communicate known customer interests in Performance Max. These themes guide the system; they do not operate as an exact list of keywords that exclusively controls delivery.