Slicing and PSD Files
MrVon,
PSD files are created with Adobe Photoshop. PSD = Photoshop Document.
Slicing is a tool you use in Photoshop. Once you design your layout, you can select areas with the slicing tool and tell the program what you want to name those images once you are done. When you are finished you can simply export all or just the selected slices as any image type (ie. GIF JPG PNG). Each image is saved as a separate image file but your original layout stays in tact.