What is the General Usage of wp_title() function
The wp_title() WordPress Function is used for display or retrieve page title for all areas of blog
By default, the page title will display the separator before the page title, so that the blog title will be before the page title. This is not good for title display, since the blog title shows up on most tabs and not what is important, which is the page that the user is looking at.
Read more information about the wp_title() function in the WordPress Codex Reference Page – wp_title()