PDFMerge is a handy way to merge multiple PDF pages into one document whether it's been fragmented for some reason or you can only display one page at a time.
PDFMerge uses a simple GUI that allows you to select the PDF documents you want to merge and then in a click, merge them into one. PDFMerge is useful, for example, if you're printing out something that will only display or save data into one PDF document at a time.
One example where PDFMerge could be useful is with Google Calendar which in the monthly view, only allows you to print one page at a time. If you want to print out a whole year, this would involve 12 PDF prints at once but with PDF merge you can simply drag and drop PDFs onto the PDFMerge interface, which lets you rearrange and rotate files.
PDFMerge is a simply but effective tool for anyone who has ever had the conundrum of wondering how to put several PDFs together into one easy to read document.