Plain labels are just small pieces of special paper made to print over it. They are generally used to print barcodes to be used by the retail and manufacturing industries. These labels generally come in rolls, but other formats are also available, depending on the supplier. For instance they can come in sheets or fanfolded. Also, plain labels come in a variety of sizes and paper types, with different kind of adhesives. These labels are normally found in white colour, without absolutely any kind of previously printed material onto them.
Not all plain labels use a similar type of paper. In fact, the kind of paper used will depend on the type of application they are going to support and also the kind of printer that will be used on the operation. Some labels are also specifically designed to support hard environmental conditions, such as high temperatures and high humidity zones. Some models are designed to last a long time while others are just made to support a few days without starting to suffer from degradation. Of course, price of these labels will depend on all these characteristics.
There are many suppliers of plain labels around the world. Normally, they attend industries like retail and logistics, but they are also found on other industries like pharmaceuticals and aeronautics. Plain labels are normally accessories of the barcode printing process, so suppliers generally also sell printers, dispensers, rewinders and all the related devices and equipment to support a successful barcode printing operation. Although it is possible to find suppliers specialized only in selling printing accessories, like labels and rewinders for example, you have to be very careful when buying labels for your operation because some difficulties can be found when trying to use non standard labels on equipment produced by different manufacturers. It is better to invest some time in testing than to discover problems when you have already bought large quantities of useless material.