Is EntityState.Modified required for an update?

I've seen a lot of people when updating a record use:

...
ms.Status = status;
db.Entry(ms).State = EntityState.Modified;
db.SaveChanges();

Is this line required? I was able to do an update without it.

db.Entry(ms).State = EntityState.Modified;

I was wondering what this statement is actually used for if the context already knows it should update that record without you specifying it explicitly then why bother specifying it explicitly?