Rib jersey fabric is a type of knit fabric characterized by raised vertical ridges (or "ribs") and furrows that run lengthwise on the fabric. It's made using a double-knit construction, which involves two needles and two sets of yarns, resulting in a fabric that is thicker and heavier than a single-knit fabric. This fabric is typically stretchy and flexible, making it ideal for garments that need to conform and move with the body, such as tank tops, T-shirts, and certain types of sportswear.

Here's how you can take care of rib jersey fabric:

1. Washing: Rib jersey can typically be machine washed in warm water. However, always check the garment's care label for specific instructions, as some rib jersey items may require cold water or hand washing to maintain their shape and color.

2. Detergent: Use a mild detergent suitable for cotton fabrics. Avoid using bleach unless the fabric is white; bleach can damage and discolor colored fabrics.

3. Drying: Rib jersey can generally be tumble dried on a low heat setting. However, to minimize shrinkage and prolong the life of the garment, consider air drying instead.

4. Ironing: If necessary, rib jersey can be ironed on a low to medium heat setting. To prevent damage, iron the garment while it's still damp, and always iron on the reverse side if possible.

5. Storage: Store rib jersey garments in a cool, dry place. Fold them neatly to prevent wrinkling.

6. Stains: Treat stains promptly. Apply a small amount of stain remover to the affected area and gently rub it in before washing the garment. Avoid rubbing too hard, as this can damage the fabric.

Remember to always follow the specific care instructions provided on the garment's label for the best results.