# Model Binding and Validation

Model Binding and Validation: Model Binding and Validation: an overview, Data Annotations and ModelState, Client-Side Validation.

Updated: November 3, 2026

1. [Model Binding and Validation: an overview](https://www.ask-codey.com/lessons/model-binding-and-validation-an-overview) (Apprentice): Never trust what a form sends. Validate on the server every time, and in the browser too for quick feedback; ASP.NET Core does both from one set of rules on the model.
2. [Data Annotations and ModelState](https://www.ask-codey.com/lessons/model-binding-and-validation-data-annotations-and-modelstate) (Journeyman): Put validation rules on the model with data annotations such as \[Required\], \[StringLength\] and \[Range\]; check ModelState.IsValid in the action; add your own errors with AddModelError; and show the messages with validation tag helpers.
3. [Client-Side Validation](https://www.ask-codey.com/lessons/model-binding-and-validation-client-side-validation) (Apprentice): Browsers check HTML attributes such as required on their own; ASP.NET Core's validation scripts check your model's data annotations in the browser, from the data-val attributes the tag helpers write.

Source: https://www.ask-codey.com/courses/csharp-full-stack-bootcamp/topics/model-binding-and-validation