Raster and Vector Data are the two main formats for producing images and graphics through a computer. All photos, images and text is made up of one or the other.
Raster Images are made up of individual dots (known as pixels), and are acquired by a scanner, digital camera, mobile phone or other raster imaging device. These can edited in software programmes such as Adobe Photoshop or the like.
A rule of thumb when producing Raster images for printing, is to produce them to a minimum of 300dpi (dots per inch) and then to save them to the actual size of the image being used within the document to be printed. (If you double the size of a Raster image within a document, you will half the quality of the finished photo or graphic when printed).
Vector Images are made up of lines rather than dots, which produce a far smaller file size and can be enlarged up to any size without any loss of quality of the finished printed image. They are also faster and easier to manipulate in most software packages.
Vector images can be produced and edited in programmes such as Adobe Illustrator, In-Design, Quark Xpress, Coreldraw and Microsoft Publisher or Word.
All text is produced as Vectors rather than Rasters (unless that text is produced in Adobe Photoshop. This is not a good idea, because when this text is enlarged it can become very pixelated and a poor quality image).
When you next supply your local print company with something to print, make sure as much of the composition as possible is made up of Vector Images and supply your files as a High Res PDF File (This is an Adobe Acrobat format and will save in both Vector and Raster formats, or a combination of both).