Elements exist in three primary states on Earth. These primary states include solids, liquids, and gasses. A liquid state would include water, hydrogen peroxide, or acetone. Examples of gasses include helium (used to fill balloons,) carbon dioxide (we breathe this out,) and carbon monoxide (emitted by engines.)
Finally, solids include any material that isn't a liquid or a gas—ice, granite, aluminum, glass, etc. There is a fourth state of matter that is the most common form in the universe and that is plasma. Two examples of plasma include lightening and the sun.