So, you have a question or two or three about Lightroom Libraries/Catalogs. Not to worry, Adobe have provided a TechNote , which is aimed at addressing questions such as:
Note: with the introduction of Lightroom version 1.1 Adobe have replaced the term "Library" with "Catalog"
1. How many files can I have in my library?
2. What is the largest photo size I can import into Photoshop Lightroom?
3. Can I have more than one library?
4. Can I store my library on a network drive?
5. How can I use my library on multiple computers, such as a laptop and a desktop?
6. How do I move photos from one library to another library?
7. How can I back up my library?
8. How can I transfer images from my hard disk to an external hard disk or to a CD/DVD when I run out of space? What happens to my library if I do this?