Oswald is a sans-serif font. It goes well with Garamond Premier, Arial, Roboto, Manus, Open Sans, Merriweather, Oxygen, Eczar, Apple System and Quicksand. If you're thinking about using Oswald then try 18px for headers. Give 16px a shot for content.
People commonly tag it as design, conference, portfolio, agency, article, health, list, event, informal and writing. You can get it from Font Squirrel, Google Web Fonts and Typekit.