David Nield writes: “More than 30 years after Adobe came up with it, the PDF file remains essential for archiving, sharing, and publishing. It’s no surprise that commercial PDF software tools are in high demand. But you don’t necessarily have to pay to process these documents, especially for basic editing operations. A host of PDF tools are available on the web that will let you quickly and easily manipulate your documents for free (with more advanced features and usage limits available for a price).”