A screen recorder app is an application that allows you to record the activity on your computer or mobile device's screen. With a screen recorder app, you can capture everything that happens on your screen, including video and audio, as well as any on-screen actions, such as clicks and keystrokes.

Screen recorder apps are commonly used for creating video tutorials, recording gameplay, capturing online meetings or webinars, or simply sharing something interesting or funny happening on your screen with friends or colleagues.

Most screen recorder apps come with a range of features, such as the ability to record in high definition, edit and trim the recorded video, add annotations or captions, and share the video directly to social media platforms or video hosting websites.

Screen recorder apps are available for desktop computers, laptops, smartphones, and tablets, and can be downloaded from app stores or as standalone software from developers' websites. Some apps are free to use, while others may require a one-time purchase or a subscription fee.