In Photoshop, the grid is a visual aid that can span the entire canvas or document area. It is used to help with alignment, composition, and spatial relationships within your design or artwork. The grid itself can be customized in terms of spacing, color, style, and visibility.
To enable and configure the grid, you can go to View > Show > Grid or press Ctrl + ' (Windows) or Cmd + ' (Mac). To adjust the grid settings, you can go to Edit > Preferences > Guides, Grid & Slices (or Photoshop > Preferences > Guides, Grid & Slices on Mac). Here you can set the grid's spacing, color, and style according to your specific needs.
The grid does not affect your image or design; it serves purely as a reference tool.