The portable band saw gets its name from the blade it uses to make cuts. The saw blade is in a continuous band (like a rubber band) and it is turned by the motor inside the saw. You don’t do the cutting, the saw does. The continuous band extends the life of the blade by insuring that the cutting takes place over the entire length of the blade instead of in a small area (like a hacksaw or reciprocating saw) and keeping it much cooler.

Makita 2107F Portable Band Saw

This example is the Makita 2107F Portable Band Saw. Sold at many home improvement and tool centers for about $300. It features variable speed and quick blade changes.Portable band saws are typically used for cutting metal such as steel pipe or iron balusters. They can usually cut something as large as 4 inches in diameter.
They require a steady hand for a cut straight and to keep the blade from binding.