HTML and CSS Lessons: : A div is block level element commonly used to identify large sections of a website, helping build the layout and design. : A span on the other hand, is an inline element commonly used to identify smaller sections of text within a block level element, such as a paragraph.
The box model: Every element on a page is a rectangular box.
state machine acts as state machine aasm gem
form_for fields_for – to switch the model in the form – like embedding one forms for into another.