The Default Page Title is the page title that is applied to any page that does not have a specific title assigned to it. You will want to set this right away as you are working on your site so that your pages will have a name whether or not you remember to give each new page a name. Ultimately, you will want to name each page its own name. This will be part of your site positioning campaign also know as search engine optimization (SEO). Page names need to be relevant to the content of that page. Search engines regard page names very highly in terms of their what the author considers to be most relevant about that page.
Additionally, you may brand all of your pages by setting the Site Title. The site title is appended to the page title with a separating dash " - ". If the page title is not defined for a particular page, the default page title will be used and the site title will NOT be appended. This is because the default page title and the site title are often both just the name of the website or the company.