What does "bias" mean in terms of fabric orientation?

In the context of fabric orientation, "bias" refers specifically to the direction at a 45-degree angle to the warp (lengthwise threads) and weft (crosswise threads) of the fabric. This bias direction is significant because it imparts unique properties to the fabric, such as greater stretch and flexibility compared to the straight grain (lengthwise or widthwise). This characteristic makes bias cuts particularly useful in garment construction, as they allow for a more form-fitting design and better drape around curves. Understanding the bias is essential for anyone working with fabrics, as it influences how the material behaves when sewn and how it conforms to shapes.