This document discusses important packages for app development. It introduces NuGet, which makes it easy to add, update, and remove libraries and tools in Visual Studio projects using the .NET Framework. Some useful packages mentioned include Microsoft.Net.Http for handling HTTP requests, Newtonsoft.Json for serializing and deserializing JSON, Coding4Fun.Toolkit for popup controls, the Live SDK for enabling Live account login, and the Windows Phone Toolkit for features like live tiles. The document encourages using NuGet to install these packages and provides examples of how to integrate them into apps.