Progressive web apps (PWAs) are a type of mobile app that combines the features of a traditional mobile app with those of a website. PWAs are built using web technologies such as HTML, CSS, and JavaScript, and can be accessed through a web browser like a website. However, they can also be installed on a device and function offline, just like a native app. PWAs offer many of the benefits of native apps, including offline functionality and push notifications, without the need for app store approval or installation.

In summary, there are several different approaches to mobile app development, including native app development for specific platforms, progressive web app development using web technologies, and cross-platform app development using tools like the Ionic framework. Each approach has its own benefits and trade-offs, and the best choice will depend on the specific requirements and goals of the app being developed.