> For the complete documentation index, see [llms.txt](https://yanxiaodi.gitbook.io/xamarin-mvvmcross-handbook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://yanxiaodi.gitbook.io/xamarin-mvvmcross-handbook/using-mvvmcross-to-create-your-first-xamarin-app/creating-the-uwp-project/understanding-the-data-binding-syntax.md).

# Understanding the data-binding syntax

As we mentioned before, the default data-binding type in UWP is `One-Way`, so we need to set a specific value as `TwoWay`:

```markup
<TextBox Text="{Binding UserName, Mode=TwoWay}"></TextBox>
```

Now you can get an app shown below:

![](https://847068821-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-LPK_0Nj6gmm5SSTHfcs%2F-LPPS0nlDt4iXUQNE2Qb%2F-LPPSNv8-j-uB8SGbE31%2Fimage.png?alt=media\&token=07a2c1ee-35f4-46b6-b950-b11956bb3207)

In the next section, I will add some real API Services to get some data from the online APIs and add some commands.