Image hosting service
Image hosting is a service that allows induviduals to have the ability to upload different types of images to the internet. The image host will then store the image onto its server, and show the induvidual different types of code to allow others to view that image.
How it works
The image host will put a form in which you can Browse through the files on your computer and select one.(Screenshot) After selecting an image, the induvidual will press a "Submit" button to upload that file to the image host's server.
After this process, the image host will often show you a number of ways you can show this image to others. The most common ways are:
Usually, the image host will put restrictions on the maximum image size allowed, or the maximum space/bandwith allowed per user.
Tools
Image hosts also allow tools such as the ability to create photoblogs/galleries with your images, or add them to a slideshow for easier viewing. Some offer more advanced tools such as the ability for an induvidual to add notes to an image they uploaded, transloaders, or browser sidebars.
Cost
Most image hosts are free. However, many have optional paid image hosting functions that are often really cheap and affordable in exchange for many less restrictions on image uploading.