Stetho is a tool that allows developers to inspect and debug their mobile applications, similar to the tools available for web development. By using Stetho, developers can see the network requests made by their app in Chrome Developer Tools, allowing them to identify performance issues and optimize their code. The author of this article shows how to use Stetho with Picasso, a popular image loading library, to load images from URLs and display them in an Android app. With Stetho, developers can also inspect the view hierarchy and database of their app, making it easier to debug and optimize their mobile application. By adding Stetho to their project, developers can gain more insight into their app's behavior and improve its performance.