What is the purpose of a squinch in dome architecture?

A squinch serves the essential architectural function of facilitating a smooth transition from a square or rectangular space to a circular dome. When constructing a dome over a square structure, simply transitioning from a square base directly to the curve of a circular dome can be structurally complicated. Squinches are built into the corners of the square and curve outward, effectively bridging the gap and allowing the dome to rest securely atop the square supports.

This structural innovation not only supports the dome but also distributes weight more evenly, making it an integral part of the design, particularly in certain architectural styles such as Byzantine and Islamic architecture. The other options, while relevant discussion points in architecture, do not accurately define the primary purpose of a squinch in dome construction.