In Java, Matchers are part of the Hamcrest library, which is a framework for writing matcher objects for unit testing. Matchers allow you to write expressive and readable tests by providing a way to specify expected results in a declarative way.

Matchers are used in conjunction with a testing framework such as JUnit or TestNG. Here are some examples of Matchers:

1. equalTo: Matches if the actual value is equal to the expected value. For example: assertThat(5, equalTo(5)).

2. not: Matches if the actual value is not equal to the expected value. For example: assertThat(5, not(equalTo(6))).

3. anyOf: Matches if any of the matchers in the list match the actual value. For example: assertThat(5, anyOf(equalTo(4), equalTo(5))).

4. allOf: Matches if all of the matchers in the list match the actual value. For example: assertThat(5, allOf(greaterThan(4), lessThan(6))).

5. containsString: Matches if the actual value contains the specified string. For example: assertThat("Hello, world!", containsString("world")).

6. hasSize: Matches if the actual value has the specified size. For example: assertThat(Arrays.asList(1, 2, 3), hasSize(3)).

7. is: Matches if the actual value is the same object as the expected value. For example: assertThat("Hello", is("Hello")).

By using Matchers, you can write more expressive and readable tests that clearly specify the expected results. Matchers can make your tests easier to understand, maintain, and extend, and can help you catch bugs early in the development process.