Today's post is going to be a little technical but I hope it will help people choose the best file formats for their graphics, charts and other visual elements in their patterns. As always, this is based on my own experience and the software that I have available to me, on the operating system that I use. Don't be afraid to question any of this and run your own tests. If you are printing your patterns through a professional printer, be sure to ask them what settings and file formats they recommend.

A little background. Skip this if you are in a rush.
In the mid 90s I was working at the Boston Globe in the Advertising Production department and, despite the fact that newspapers may be one of the slowest industries to embrace new technology (ask me about Atex sometime) we had begun to accept PDFs from customers sending in their ads. In the time after x-acto knives and real dark rooms, but before the invention and wide acceptance of PDF technology, departments, like the one in which I worked, kept Macs and PCs running PageMaker, Quark, Illustrator, Freehand and often a few more obscure layout programs, in various versions to accomodate the vast variety of files that might come in from customers. Even if we had the software to open someone's file, we still had to contend with the fonts. Oh the fonts. PC fonts wouldn't run on Macs and vice versa (still the case for most older fonts, but OpenType fonts are now cross-platform), the fonts from Company A might conflict with the version from Company B, already running on that machine, and all of this was before the ad ever hit the RIPs. These were the hurdles we faced in ensuring that the advertiser's ad looked the same when it left their computer as it did when it printed out on that dingy newsprint, a few days later. Even if the advertiser had the forethought to send an EPS file, there was still a strong likelihood that some percentage of the files would have font problems, and worse, once in EPS format, there was little we could do to resuscitate the ad if there were a problem.
I realize to the younger amongst you, that all this sounds a bit old fashioned and silly. One might wonder if I also had to walk six miles, uphill, both ways, in the driving snow, in my bare feet, just to get to work. To you I say, "pull up your pants, get a haircut and get off my lawn."
But in all seriousness, the PDF file format was a huge boon to publishers like newspapers. Finally, an entire ad, built in any program, on any operating system, using any fonts, could be delivered to a printer anywhere and the printed file would look just like it did back at its birthplace. Even the company using Ventura Publisher and their own custom made fonts, was able to get great results from anyone printing their files.
Knit and crochet designers have benefited from this technology too. Not only can we provide customers with a file format that can be opened on just about any computer using, a free application, but we can be sure that the text will look and flow the same way wherever the pattern is viewed or printed. I don't think it's hyperbole to state that, second to the internet itself, the PDF file format is one of the primary reasons it is so easy for independent designers to self publish.