acid in memorabilia used in the scrapbook. Older "magnetic" albums are not acid-free and thus cause damage to the photos and memorabilia included in them. Gloves, too, are used to protect photos from the oil on hands. An international standard, ISO 18902, provides specific guidelines on materials that are safe for scrapbooking through its requirements for albums, framing, and storage materials. ISO 18902 includes requirements for photo-safety and a specific pH range for acid-free materials. ISO 18902 prohibits the use of harmful materials, including Polyvinyl chloride (PVC) and Cellulose nitrate. Digital scrapbooking The advent of scanners, desktop publishing, page layout programs, and advanced printing options make it relatively easy to create professional-looking layouts in digital form. The internet allows scrapbookers to self-publish their work. Scrapbooks that exist completely in digital image form are referred to as "digital scrapbooks" or "computer scrapbooks". While some people prefer the physicality of the actual artifacts they paste onto the pages of books, the digital scrapbooking hobby has grown in popularity in recent years. Some of the advantages include a greater diversity of materials, less environmental impact, cost savings, the ability to share finished pages more readily on the internet, and the use of image editing software to experiment with manipulating page elements in multiple ways without making permanent adjustments. A traditional scrapbook layout may employ a background paper with a torn edge. While a physical page can only be torn once and never restored, a digital paper can be torn and untorn with ease, allowing the scrapbooker to try out different looks without wasting supplies. Some web-based digital scrapbooks include a variety of wallpapers and backgrounds to help the users create a rich visual experience. Each paper, photo, or embellishment exists on its own layer in your document, and you can reposition them at your discretion. Furthermore, digital scrapbooking is not limited to digital storage and display. Many digital scrappers print their finished layouts to be stored in scrapbook albums. Others have books professionally printed in hard bound books to be saved as keepsakes. Professional printing- and binding-services offer free software to create scrapbooks with professional layouts and individual layout capabilities. Because of the integrated design and order workflow, real hardcover bound books can be produced more cost effectively. Early digital scrapbooks were created from digital photos uploaded to an external site. Over time, this moved to a model of downloading software onto a