Notebook app is a mobile application that helps you create notes and provides facility to save and edit them. The functional description of these apps may include the following basic features

1. Create and save notes: These apps help you create new notes and save them, so that you can refer to them later.

2. Sorting and Editing: You can sort and edit notes, which generally do a variety of things including editing text, formatting, adding images, adding links, etc.

3. Categorizing: You can organize your notes into different categories or tags, so that you can easily find the notes you need.

4. Short notes: You can make short notes, which helps to store information quickly and briefly.

5. Combined media: Some notes can be embedded where you can attach image links, audio file links, or more detailed information