A raster image is made of pixels arranged in a grid. Pixel dimensions describe that grid, such as width multiplied by height. File size describes the bytes used to store the image; these are related but different measurements. Two images with the same pixel dimensions can have different file sizes because of format, compression, and visual detail. Enlarging an image does not recreate detail that was never captured. Display size also affects whether the available pixels look sharp to the viewer. For an article illustration, use enough detail for the intended display without uploading unnecessarily large files. Keep an original before editing. Cropping changes composition and dimensions, while resizing changes the pixel grid. A screenshot of text is usually less adaptable than actual text in the page. Practice: Compare the dimensions and file sizes of two images. Describe which factors might explain the difference without assuming that the larger file always looks better.