This guide is about how to automatically add form submissions to a Notion database in a Next.js app using Netlify forms. To start, you need to set up your Notion integration and create an internal integration token, then share your desired database with the integration. You'll also need to install the `@notionhq/client` package to make working with the Notion API easier. Then, in your Next.js app, you can create a form using HTML and add it to Netlify, where you can configure the form submission settings. To send the data to Notion, you'll need to set up a serverless function that uses the `@notionhq/client` package to create a new record in the database. You can then deploy your project to Netlify and test the form submissions in your Notion database.