Final answer:
To edit a PNG without losing transparency, use editing software that supports transparency, such as Photoshop or GIMP; maintain transparency when opening the file, edit on a separate layer, and save the PNG with the correct format options to preserve the transparent background.
Step-by-step explanation:
To edit a PNG without losing transparency, you can use photo editing software that supports layers and transparent graphics, such as Adobe Photoshop, GIMP, or Paint.NET. First, make sure to maintain the PNG's transparency when opening the file; it should display a checkered or transparent background indicating that no color is applied. If the background is not transparent, the image might not have been saved properly as a transparent PNG in the first place.
Once you have the file open, use the software's tools to edit the image while preserving transparency. For example, if you need to erase part of the image, make sure you are using an eraser tool that is set to affect only the image and not the transparent background. If adding new elements, add them on a separate layer above the PNG to maintain the original image's transparency. When saving your edited file, select the PNG format and ensure that any options for maintaining transparency are enabled, which will likely be the default setting for a PNG.
Remember, not all software will maintain PNG transparency when saving the file, so it's essential to select the correct format options during this final step.