The Facebook app provides features such as connecting with friends and family, sharing updates, photos, and videos, joining interest groups, following pages for entertainment or news, engaging in live video streaming, using a marketplace for buying and selling items, and interacting with businesses.

Facebook is free to download and use. Users can create an account and access most features at no cost. There may be optional in-app purchases, such as premium features in games or applications, but these are not required to utilize Facebook's core functionalities.

Facebook employs various privacy and security measures, including customizable privacy settings, encryption, and security protocols. Nonetheless, users should be cautious about sharing personal information online and remain aware of potential data breaches.

Yes, Facebook can be accessed on multiple devices at the same time. Whether on a smartphone, tablet, or computer, users can log in and access their feed, messages, and notifications. Facebook synchronizes activity across devices for seamless switching without data loss.

If facing issues with the Facebook app, try restarting the app or device, and ensure the app is updated to the latest version. If problems continue, visit the Facebook Help Center for troubleshooting or support, or contact Facebook's customer support for further help.