Read original post by Chris Veeningen at Playing with .Net
A big percentage of all apps is showing data to the user, formatted in different ways. Sometimes it are images, the other time graphs, but a lot of times you use a data grid to present your data to the user. To present this data in the most smooth way to the user, you often want to make the columns / rows scalable. With this approach the data is shown in the most comfortable way to the user when they use different devices and resolutions. When using XAML in your Windows 8 metro style app, you can easily define a dynamic layout for your grid by using the ColumnDefinition and/or RowDefinition classes.