Radio Buttons are really helpful for HTML Forms to get a choice of input from users. Radio buttons operate as a group and provide mutually exclusive selection values. A user can select only one option in a radio button group.
Take a Look at the following view of default radio buttons in a HTML
When it comes to selecting the radio button, take a look at the following view of after selecting the radio button and how it looks like.
Although default radio buttons gives a clean output in a webpage but when it comes to User Interface and User Experience one can feel really odd filling the form in the default radio buttons.