How is Modelstate.IsValid triggered?

namespace SampleMapper.Models;

public class Driver
{
    public Guid Id { get; set; }
    public string FirstName { get; set; } = "";
    public string LastName { get; set; } = "";
    public int DriverNumber { get; set; }
    public DateTime DateAdded { get; set; }
    public DateTime DateUpdated { get; set; }
    public int Status { get; set; }
    public int WorldChampionships { get; set; }
}

[HttpPost]
    public IActionResult CreateDriver(DriverCreationDto data)
    {
        var _driver = _mapper.Map<Driver>(data);

        if(ModelState.IsValid)
        {
            drivers.Add(_driver);

            return CreatedAtAction("GetDriver", new {_driver.Id}, data);
        }

        return new JsonResult("Something went wrong") {StatusCode = 500};
    }