Large-format printing, sometimes also known as wide-format printing, is an industry term that is used to describes projects that require especially large machines to handle. Most shops consider anything between 18" and 100" in width to be a wide format. Once you go above that width, you're talking about super-wide format.
What Large-Format Printing Is Used For
Outdoor advertising is one of the more popular applications of wide-format printing. For example, many billboards are made up of several strips of large-formatted material. Banners are also popular items that people take to shops with these capabilities.
Digging into the Details
DPI, dots per inch, is the standard measurement for the level of detail that goes into all printed products. Doing a print run at a high DPI tends to slow things down and consume more ink. For that reason, large-format printing projects are often performed at lower DPIs.
At very large scales, such as billboards or draped displays that are only seen at far distances, a 120 DPI image should be sufficient. The closer your target audience is expected to get to the product, the better you will want the DPI level to be. Banners can usually be printed at 150 DPI, but you may need to go up to 300 DPI is there's small text included. Generally, using small text on a large-format product is considered bad form, and you should consider eliminating or resizing the text for better long-distance readability.
Make It Bleed
Another term that is used to describe all printed items is bleed. This refers to how close the ink actually gets to the edge of the finished item.
Printing at what is called "full bleed" is typically more expensive. This is because the edges have to be trimmed down to eliminate white space. When printing a banner, you may be able to get away with doing less than full bleed. If the item in question is going to be used for anything that has to be overlapped to complete the display, such as a billboard, then you'll likely need a full-bleed print run.
If you're sending your own digital files to the printer, make sure you'll be using something they can utilize on their systems. Most companies are using some form of the Adobe Suite or a similar program. If you're not, you can still export to a PDF file format to maximize compatibility.