Spot color is how most logos, text and flat graphics are printed. A three-color design on a white tee means three screens and three inks, each laid down as a solid area. Because each ink is mixed to order, spot colors can match a brand color closely and can be any ink type: plastisol, water-based, metallic, puff or fluorescent.
The trade-off is that setup grows with every color. A dark garment usually adds a white underbase screen, and each print location needs its own set of screens. Designs with gradients or photos do not suit pure spot color unless the shading is converted to halftones.
When ordering, give Pantone (PMS) references for any color that must match, and expect fabric color and texture to shift how an ink reads. Ask how many screens your design needs and whether two similar colors could be merged. The separations guide compares spot color with the alternatives.