What does the Expand function do in Illustrator?

The Expand function in Adobe Illustrator is primarily used to convert certain types of objects into vector paths. When you use the Expand command, it takes complex objects, such as effects, strokes, and patterns, and breaks them down into individual vector paths. This transformation allows further editing and manipulation of these components as separate entities, enabling designers to achieve precise control over their artwork.

For instance, if you've applied a gradient to a shape or used a stroke, expanding these objects allows you to convert them into filled shapes that can be further edited without the original effects or attributes. This is crucial for tasks such as editing shapes after rasterizing them or ensuring compatibility with applications that might not support certain effects.

In contrast, scaling objects simply changes their size, merging layers combines multiple layers into a single layer without altering their vector nature, and changing the color mode of objects involves adjusting the color profile or format rather than converting them into vector paths. Each of these functions serves a different purpose, but the distinctive capability of the Expand function is its focus on modifying the structure of objects into editable vector paths.