AI -- Adobe Illustrator -- is the default file type for Illustrator which saves completely editable and scalable vector graphic images. Certain AI files are viewable with PDF readers; however, they will not allow you to edit the file's layers or individual elements.
EPS stands for Encapsulated PostScript. An EPS file can contain text as well as graphics. It also usually contains a bit map version of the image for simpler viewing rather than the vector instructions to draw the image. Learn more about .EPS files: Visit the Adobe Illustrator website. Search for answers to .EPS-related questions on IT Knowledge Exchange.
JPEG bitmap. JPG is a file extension for a lossy graphics file. The JPEG file extension is used interchangeably with JPG. JPEG stands for Joint Photographic Experts Group who created the standard. JPG files have 2 sub-formats, JPG/Exif (often used in digital cameras and photographic equipment), and JPG/JFIF (often used on the World Wide Web).
Portable Document Format (PDF) is a file format used to present and exchange documents reliably, independent of software, hardware, or operating system. Invented by Adobe, PDF is now an open standard maintained by the International Organization for Standardization (ISO).
A .PSD file is a layered image file used in Adobe PhotoShop. PSD, which stands for Photoshop Document, is the default format that Photoshop uses for saving data. PSD is a proprietary file that allows the user to work with the images’ individual layers even after the file has been saved.