Image content type is a great way to upload images of various kinds and represent them in a gallery. For any of the other content types, you can upload a picture in your HTML editor and display the image. Image content type comes with a feature that allows it to be resized dynamically and displayed as a thumbnail or in a preset dimension. You can enable preset dimensions from Administer » Site configuration » Image. You can configure the number of images that appear in a gallery from Administer » Site configuration » Image Gallery.

For more sophisticated gallery functions enable the gallery2 module from your installation.

Resources

Gallery2 module

Video

In this video you will see how to upload image content types on your Drupal CMS system