HTML (Hypertext Markup Language) is the primary language used to represent content on web pages. For example, it allows the the web browser to determine which parts of the content are headings, which parts are paragraph text and which parts should be formatted as tables.
CSS (Cascading Style Sheet) is the primary language used on web pages to describe what visual appearance content should have. For example, it allows the the web browser to determine what size text should be, what color the background of a heading should be or the spacing between two elements on the page.
A Laravel Collection is a convenient wrapper around arrays providing methods for manipulating the array data in useful ways.