?Explain how media files used in a PowerPoint presentation can be compressed.

What will be an ideal response?

Answers will vary. When you save a presentation that contains photos, PowerPoint automatically compresses the photos to a resolution of 220 pixels per inch (ppi). Compressing photos reduces the size of the presentation file, although it also reduces the quality of the photos. To change the compression settings, select a photo, and then in the Adjust group on the Picture Tools Format tab, click the Compress Pictures button to open the Compress Pictures dialog box.?If you insert additional photos or crop a photo after you applied compression settings, you will need to reapply the settings. Photo compression is not permanent until you close the file. This means if you compress photos to a lower resolution and then change your mind and want to decompress them to the default resolution, you can do this as long as you have not closed the file. Once the compression settings are permanently applied, you cannot undo them because the extra information has been discarded.?As with pictures, you can compress media files. If you need to send a file via email or you need to upload it, you should compress media files to make the final PowerPoint file smaller. To do this, click the File tab to display the Info screen in Backstage view, and then click the Compress Media button. The more you compress files, the smaller the final presentation file will be, but also the lower the quality. When you compress videos, any parts of videos that you trimmed off will be deleted, similar to deleting the cropped portions of photos. Please see the section "Compressing Pictures and Media" for more information.