Matching Rules #inSalesforce

A matching rule compares field values to determine whether a record is similar enough to existing records to be considered a duplicate.

For example, a matching rule can specify that if the Email and Phone values of two records match exactly, the records might be duplicates.

You can use the provided standard matching rules with duplicate rules and duplicate jobs. You can’t edit these standard matching rules, but you can create custom matching rules.

Note : Use matching rules with duplicate rules to define what happens when duplicates are identified.

Reference: 

https://help.salesforce.com/s/articleView?id=sf.matching_rules_standard_rules.htm&type=5

https://help.salesforce.com/s/articleView?id=sf.matching_rule_map_of_reference.htm&type=5