What do you call the series of vertical and horizontal lines that cover the composition in After Effects?

The correct term for the series of vertical and horizontal lines that cover the composition in After Effects is referred to as a "Grid." The grid serves as a visual reference that aids in aligning and positioning elements within your composition. It’s particularly useful for maintaining balance and symmetry in your design, allowing for precise placement and consistency.

The grid helps artists and animators visualize space, making it easier to create structured layouts or to compose shots according to design principles. This tool can be toggled on or off as needed and can also be customized in terms of spacing to suit the needs of any particular project, enhancing both workflow efficiency and creative control.

Alternative terms like "Guide" or "Baseline" refer to different concepts in the design realm, with guides being user-placed lines that help with alignment and baselines typically refer to text layout rather than the overall composition framework. The term "Layout Grid" may imply a similar concept but is not a recognized term specifically used in After Effects to denote the grid within the composition window. Therefore, "Grid" is the most accurate choice in this context.