Lightroom never actually changes the pixels in your photos. Instead, it writes a set of instructions in the data corresponding to the enhancements you make to the photo as it appears on your monitor. If you want to use the photo file with a different application or on another computer, you need to export the edited image and make sure the changes you made in Lightroom are still visible when you open the image with another photo editor.
Understanding the Lightroom Export Feature
Explore the Export Dialog Box Settings
Create an Export Preset to Attach Photos to Your E-mail