Kazaa
Kz was released only to accommodate the Windows operating system but it can be run on Linux, Mac OS X and other operating systems with emulation software like the WINE and Virtual PC.

Kz is considered by many users as superior to other file sharing programs because of its wide file selection and fast transfer speeds. While it is the p2p network with the largest user base installed, it is worth noting that the Kz client installs adware onto the user's machine, with potential security and privacy implications.

The program uses a "participation level" system to reward participants who share a lot of material with fast downloads. Unfortunately, a feature like this is subverted by the bulk of the unauthorized clients, leaving the legitimate third-party ones toiling in suffer.

The number of users connected to the Kz network at any given time fluctuates between 1 and 5 million users, the average usually lying in the number of 3 million users approximately. There are over 1.5 billion files on the network, totaling 26 petabytes, with about 1,000 downloads every minute.

Features (kazaa.com):

• Up to five ΄Search More΄s: You can 'Search More' up to five times. This means you can access up to 1,000 results per search. Each 'Search More' displays up to an additional 200 search results score.
• Search Agent: You can use Search Agent when you are in search of a file to perform repeated queries every 30 minutes, over a 24- hour period.
• Multiple simultaneous searches: Searching is efficient because the user can run up to 24 concurrent searches.
• Multiple search result tabs: Each search you perform is displayed in a new window. This means that your search results won't be overwritten by each and every new search you perform.
• 'Quick' and 'Advanced' search tabs: 'Search' view allows both quick and advanced searches. Use the advanced search to obtain more accurate results in less time.
• Web search: You can use Kz to search the web.
• Downloading from Multiple Sources: Faster downloads as files can be simultaneously downloaded from multiple sources.
• Kz includes built-in Virus Protection from the adware BullGuard. It has been especially designed to quarantine and delete suspect files. You are also enabled to select how often you want your BullGuard program to scan the Kz for viruses and check for the latest definition updates. We must say that the BullGuard is the leading p2p virus protection software available and can be exclusively found in the Kz.
• Block suspect files with the Kazaa Virus Filter - With this feature the Kz can block: .EXE, .SCR, .LNK, .BAT, .VBS, .COM, .DLL, .BIN and .CMD in your search results, for additional safety.
• Adult Filter with password protection, ensuring your settings are secure.
• Kazaa has a No Spyware Commitment, it only has an Adware one.
• Customizable Toolbars: You can make Kazaa as streamlined or as feature packed as you want.
• Gold/Blue icons: Gold icons represent Premium content which is Artist/Content Owner approved and distributed by the Kz via Altnet. Blue icons represent all other files shared using the Kz.
• Preview files : if a file download is due to be completed or complete already, then you can Preview/Play it directly through the 'Traffic' view. Some files will open in 'Theater' view. Not all file types can be executed this way. .
• Global Reach: You will have access to millions of peers around the world with the Kazaa.
• Skype (adware): You can make free online calls, p2p. Talk, Instant Message and Send Files, PC to PC.
• Publish material you have made yourself: Simply place your photos, book, articles, artwork or independent films in your Shared Folder and users around the globe will be able to find and download them.
• Magnet Links: Magnet links allow web sites to link directly to files that can be downloaded with p2p technology. This can result in a significant cut down on online distribution and hosting costs.
• Promote your Blog: Promote your blog or website to other users via the Kz and find other users' blogs and sites.
• Unlimited bitrates. Higher quality files have been made possible with increased bitrates.
• Integrity Rating: The files are labeled by peers with reference to the technical quality and completeness of file data (metadata), so that file reliability is enhanced.
• Channels: Kz includes Search and Browse Channels. Channels are websites especially designed to be viewed within the Kazaa, giving you direct access to downloads and information.
• PeerPoints provided by Altne (adware)t: Collect Altnet PeerPoints by sharing Gold Icon Files. Altnet PeerPoints are redeemable for sponsored downloads and users stand good chances to win prizes.
• Customizable skins: Customize the basic desktop interface and create your own skin with our guide.
• Shared playlists: Create unique shared playlists and search for other Kazaa users playlists.
• Media Player image handling: View images and play audio and video files within the built-in Media Player in 'Theatre' view.
• Kapsules: Kapsules - custom digital packaging of multi-file collections. For example, a Kapsule may include music, exclusive footage of live performance, lyrics and images - all by the same band or artist.

Right at this point we have to comment that Kz is 100% Legal. On December 19, 2003, the Dutch Supreme Court confirmed upon the legitimacy of the Kazaa p2p technology and its distribution.
(8 points )

LimeWire
Following in the Kazza's footsteps the LimeWire runs on the Gnutella Network. It is an open standard software running on an open protocol, free for the public to use. The Limewire allows you to share any file. It is written in Java, and will run on Windows, Macintosh, Linux, Sun, and other computer platforms.

You can search for multiple files at the same time, available in several different languages and different platforms (famous for its easy-to-use and cross-platform compatibility). Yet, though the LimeWare can be operational through Sun Java Runtime Library, it cannot operate likewise via the Microsoft Virtual Machine Java. The number of Hosts connected to the LimeWire network at any given time, fluctuates between 1,2 million and 1,8 million, the average normally being approximately 1,4 million.

Features (limewire.com):

• No bundled software of any kind. No spyware. No adware.
• Firewall to Firewall Transfers: About 60% of the users are currently firewalled resulting in an increasing amount of content on the network.
• Faster network connections: Using new "UDP Host Caches", Lw starts up and connects very fast.
• Universal Plug 'N Play: UPnP support allows the LimeWire to find more search results and produce faster downloads.
• iTunes Integration: Windows users can take advantage of the LimeWire's iTunes integration.
• Creative Commons Integration: the LimeWire recognizes OGGs and MP3s licensed under a Creative Commons License.
• "What's New?" feature: Users can browse the network for the most recent content additions.
• Search drill down results: Searches immediately display the artists, albums and other information that fully describes files.
• Proxy support: Users are enabled to utilize web proxies to route their downloads in their efforts to protect their identity.
• Support for International searches and International groups: Users can search without having to be acquainted with other languages since the LomeWire ensures that they will be connected to other users in their own language. The aim of the facility mentioned is to aid international users to receive search results in their native language and to find content from sources that are close to home.

The LimeWire is also capable of featuring the following facilities:

• Ability to search by artist, title, genre, or other meta-information.
• Multiple search tabbed interface.
• "Swarm" downloads by multiple hosts help you to download files faster.
• iTunes integration for Mac users.
• "Ultrapeer" technology that reduces bandwidth requirements for most users.
• Integrated chat.
• Browse host feature that even works through firewalls.
• Ask to block from downloading suspect files that may contain viruses, like executable files.
• Bitzi metadata lookup.
• International versions.
• Connects to the network using GWebCache, a distributed connection system.
• Automatic local network searches for very fast downloads. If you are on a corporate or university network, you are enabled to download files from other users on the same network almost instantaneously.
• Support for MAGNET links that allow you to click on web page links that access Gnutella.
• Custom skins.

(10 points)