What tool is commonly used for ensuring straight edges when painting?

The tool utilized for ensuring straight edges when painting is painter's tape. This adhesive tape is specifically designed to create clean, sharp lines on surfaces, allowing for precise paint application without smudging or bleeding. By applying painter's tape along the edges of the area to be painted, such as where a wall meets the ceiling or around trim, painters can achieve a professional finish that enhances the overall appearance of their work.

While brushes, rollers, and sprayers are all essential tools for applying paint, they do not provide the same capability for creating straight edges that painter's tape does. Brushes are primarily used for painting corners and detailed work, rollers cover large areas quickly, and sprayers can efficiently coat surfaces, but none of these tools can deliver the precision in edge definition that painter's tape accomplishes. Thus, painter's tape stands out as the preferred choice for ensuring clean and straight lines.