What is media hosting and what are the different types of hosting?
I don't think there are official definitions for these terms, and there is some overlap, but here are the basics as I understand them:
Shared hosting: You share a server with multiple customers. Resources such as CPU and RAM are shared by all. You have privileges only in your own user account and can't modify the server's config. Very cheap and widely available. If your website needs more than basic performance you will probably suffer from the 'noisy neighbours' who share the resources. The hosting co. manages the server software. You manage the web application.
VPS hosting: You have full administrator access to a slice of a server. Only part of the server is reserved for you, but as far as you can tell it's entirely yours. Resources are reserved. You manage the entire server, including the operating system, security and backups, although you can usually start from a pre-installed image. Requires sysadmin knowledge. Still cheap and widely available.
Cloud hosting: A modern, and still changing, variant of VPS hosting. Has about the same profile, but can usually be paid and used by-the-hour. Has an API so you can programmatically create, start, delete servers. Often used for creating a dynamically scaling infrastructure, or for running temporary test servers. Examples: Amazon EC2, Rackspace Cloud, Slicehost, etc.
Dedicated hosting: You have full admin access to an entire server. The server's hardware is usually leased or purchased from the hosting co. and hardware maintenance is done by them. You're responsible for the entire software side. Other arrangements, such as backups, vary. Server's entire resources are yours.
Colocation: You have full admin access to an entire server. Similar to dedicated hosting, but you buy the server, bring it to the datacenter and are responsible for the entire thing. If it breaks, you fix it. The hosting co. only provides power, airco and bandwidth.
Managed hosting: Depends. Usually a luxury version of dedicated hosting. The hosting co. takes care of the server, the operating system, various supported applications such as the LAMP stack, including upgrading and configuration. You basically take care of your web app and its data. Hardware support, service monitoring and emergency troubleshooting is usually done by hosting co. Pricey but comfortable. Example: Rackspace Managed Hosting.
Media hosting: Usually an extra service built on managed hosting, built for serving 'media', such as video streams for popular content. Generally it's more of an infrastructure than a single server. The hosting co. optimizes the infrastructure, including network, storage, loadbalancing, firewall, webservers, etc., to provide high-throughput, low-latency service. Can include specialized software such as Flash Media Server.
Although there are specific constraints and optimizations to HTTP (and other internet content delivery protocols) depending on the nature of the content being served, applying a blanket label of "media" somewhat undermines the semantics of a targeted solution.