Pattern matching is a fundamental mechanism in Prolog that allows the interpreter to match query patterns against available facts and rules. Prolog's pattern matching is based on the concept of unification, which is the process of finding substitutions for logical variables that make two terms identical.

Here's how Prolog implements pattern matching using unification:

1. Matching Constants : If the query pattern is a constant (e.g., an atom or a number), Prolog checks if there is a corresponding fact or rule with the same constant. If a match is found, the unification succeeds, and any variables in the query pattern are bound to the corresponding values in the fact or rule.

2. Matching Variables : If the query pattern is a variable, Prolog considers it a "wildcard" and matches it with any term. The unification succeeds, and the variable is bound to the term it matches.

3. Matching Complex Terms : If the query pattern is a complex term (e.g., a compound term or a predicate), Prolog recursively matches the subterms of the query pattern against the corresponding subterms in the available facts and rules. This includes checking for the same functor (predicate name) and matching the subterms recursively.

4. Multiple Solutions and Backtracking : Prolog attempts to find multiple solutions by backtracking. If the unification fails during the initial attempt, Prolog backtracks to the last choice point and tries alternative possibilities. This allows Prolog to explore different branches of the search tree and find multiple solutions.

5. Unification Algorithm : Prolog uses an efficient unification algorithm to perform pattern matching. The algorithm handles variable bindings, occurs-check (to prevent infinite terms), and the propagation of bindings during the unification process.