The Browser Page Title is the title that show up in the browser tab.  It is also the name of the page that shows up for Search Engine results. This is really important for SEO that the Search Engine Result Lists has a beneficial and descriptive page title.

By default, Joomla 3 will only have the Menu Item name as the Browser Page Title.  You can add the title of your site to every page with a single setting in the Global Configuration Site Tab. You may choose to have the name of your website placed before or after the Menu Item name.  There are some arguments for both, but I prefer to have the site name placed before the name of the page.

System -> Global Configuration -> Site Tab