michaels arts & crafts PDF: Stands for Portable Document Format which is used mainly for documents. PDF file format preserves fonts, page layout, and also other document information and will be imported into Photoshop for editing. PDF files are platform independent, meaning almost any computer OS can be used when opening them. PDF files aren't used in Photoshop for creating artwork. Round-the-world tickets are offered by airline alliances, a sort of partnership among groups of airline carriers. The three biggest alliances are Oneworld, Sky Team and Star Alliance. The alliance agreement makes booking round-the-world passes easier and usually cost-effective. Purchasing a round-the-world ticket from an alliance group also lets you collect mileage points inside same group, providing a good accumulation of points once you return home (to be used on the next trip!).