Developing a reliable file processing application in Go requires careful handling of file offsets, especially when counting attributes such as bytes, words, and lines. Each read operation on a file updates the file descriptor’s offset, which can lead to issues when the same file descriptor is used across multiple counting functions. This lesson explores how to address this offset problem by utilizing the `seek` method from the `os` and `io` packages to reset the file's read location before performing subsequent counts. By implementing a more efficient design using a `getCounts` function that consolidates counting logic and incorporates an interface that combines both reading and seeking capabilities, the application can handle data from both files and standard input streams seamlessly. Additionally, incorporating unit tests helps ensure that the functionality remains intact as the code evolves.