Include the content of this crawled property in the full-text index. This enables searching for the content of this crawled ...

Include the content of this crawled property in the full-text index. This enables searching for the content of this crawled property without mapping to a managed property. Use this setting if the content of this property may be relevant for end-user queries, but you do not see a need for a managed property that contains this content.For example, if the crawled property is "reviewer", simple queries such as "smith" will return both items containing the word "Smith" and items whose reviewer crawled property contains "Smith".  When not enabled, you must specify a managed property mapping, and users must specify a property filter in the query (reviewer:smith) to find the same items.  Including unnecessary properties in the full-text index may have a negative effect on search relevance and performance.