The extra files in your raster download
When you download a raster dataset (for example, aerial imagery or topographic maps), you will also find several additional supporting files.
These files contain metadata about the images, and they assist software packages to handle the images correctly.
Extra files explained by extension
Typically, for each image file, you'll find the following additional files with the same name. By extension, these are:
.tfw or .jpw:
These are world files that contain simple georeferencing information that can be used by your software to automatically position the images relative to other images and geographic data.
These files contain metadata about the image data, for example the geographic projection and raster band information.
This file contains layer metadata, such as the publisher and description
Extra files and your software application
While you don't need any of these extra files to view the image tiles directly, your software might need some or all of these files to access georeferencing information and metadata. Usually, you will need to keep the supporting files in the same folder as the image for your software to find them.