How do you mean tags? You can use an EXIF editor to embed information in the image file itself, but often what people refer to as tags is stored in a database for an image management program or an image viewing website. It also depends on what you want to do with the tags as you might have to tag a certain way in a certain format the exif data to allow it to be usable in different programs. Not all exit data is maintained when you resave an image either, it all depends. so perhaps a little more context needed mate
