A FileWriter is a class in the Java programming language that allows developers to write character data to files. It is part of the java.io package and provides methods to create, write, and append text to files easily. By using a FileWriter, programmers can store information in a file format that can be accessed later. To use a FileWriter, you typically create an instance by specifying the file's name. Once the FileWriter is open, you can use methods like `write()` to add text and `close()` to save changes and release system resources. This makes it a straightforward tool for file handling in Java applications.