What is a vector mask primarily used for in Photoshop?

A vector mask in Photoshop is primarily used for providing sharp edges and scalability. This is because vector masks are based on paths defined by mathematical equations, allowing for smooth and clean lines that do not lose quality when scaled. Unlike raster masks, which can become pixelated when enlarged, vector masks retain their clarity regardless of size. This feature makes them particularly useful for masking complex shapes or areas in an image where a high level of precision is required.

Vector masks are ideal for isolating elements of an image while maintaining clean edges, which is crucial in graphic design, illustration, and any work that demands high resolution. Additionally, users can easily manipulate vector masks using the Pen Tool and the Shape Tool, allowing for sophisticated editing without sacrificing quality.