1. Introduction 1. The emergence of decentralized applications 2. Definition of a decentralized application 3. Bitcoin as a decentralized application 4. Nomenclature and its importance 5. Classification of decentralized applications
2. The operation of a decentralized application 1. Mechanisms for establishing consensus 2. Mechanisms for distributing tokens 3. Formation and development of a decentralized application
3. The current state of type II and III decentralized applications
4. Conclusion
5. Appendix 1. A proposed metaphor for decentralized applications

A new model for building successful and massively scalable applications is emerging. Bitcoin led the way with its open-source, peer-to-peer nature, cryptographically-stored records (block chain), and limited number of tokens that power the use of its features. Several applications are adopting the Bitcoin model in order to succeed. BitShares, Mastercoin and Meshcoin are just a few of those "decentralized applications" that use a variety of methods to operate. Some use their own block chain (BitShares), some use existing block chains and issue their own tokens (Master Protocol and Mastercoin), and others operate at two layers above an existing block chain and issue their own tokens (Meshcoin).

This paper describes why decentralized applications have the potential to be immensely successful, how the different types of decentralized applications can be classified, and introduces terminology that aims to be accurate and helpful to the community. Finally, this paper postulates that these decentralized applications will some day surpass the world’s largest software corporations in utility, user-base, and network valuation due to their superior incentivization structure, flexibility, transparency, resiliency, and distributed nature.

For an application to be considered a DA, it must meet the following criteria:

1. The application must be completely open-source, it must operate autonomously, with no entity controlling the majority of its tokens, and its data and records of operation must be cryptographically stored in a public, decentralized block chain.

2. The application must generate tokens according to a standard algorithm or set of criteria and possibly distribute some or all of its tokens at the beginning of its operation. These tokens must be necessary for the use of the application and any contribution from users should be rewarded by payment in the application's tokens.

3. The application may adapt its protocol in response to proposed improvements and market feedback but all changes must be decided by majority consensus of its users.

Satoshi Nakamoto, the creator of Bitcoin described his invention as “A Peer-to-Peer Electronic Cash System[2]”. Bitcoin has been shown to effectively solve the problems that arise from a trustless and scalable electronic cash system by using a peer-to-peer, distributed ledger, the Bitcoin block chain. In addition to being a peer-to-peer electronic cash system however, Bitcoin is also an application that users can interact with through computer software). But most importantly for the purposes of this paper, based on the criteria outlined above, Bitcoin is a decentralized application. Here is why:

1. All Bitcoin software applications are open-source, no entity (government, company, or organization) controls Bitcoin and all records related to the use of Bitcoin are open and public.

2. Bitcoin generates its tokens, the bitcoins, with a predetermined algorithm that cannot be changed, and those tokens are necessary for Bitcoin to function. Bitcoin miners are rewarded with bitcoins for their contributions in securing the Bitcoin network.

3. All changes to Bitcoin must be approved by a majority consensus of its users through the proof-of-work mechanism.

Decentralized applications were initially described as Decentralized Autonomous Corporations (DAC) in an article written by Daniel Larimer, of Invictus Innovations. This papers avoids the term corporation for two reasons:

First, because it carries with it unnecessary preconceptions. For instance, a corporation is established in a jurisdiction, it has shares, a CEO, employees, etc. DAs, like Bitcoin, have none of these characteristics. In addition, the narrative is very important for the way DAs are perceived by various nations and jurisdictions. The same way that governments struggle to learn and regulate Bitcoin because the concept of currency is associated with it, governments might be compelled to regulate an open-source computer program that is a decentralized application.

Second, because traditional corporations may engage in several techniques to raise capital (like selling shares of its stock and paying dividends or borrowing against its stock and paying interest) that a DA does not need. The concept of a DA is so powerful and elegant because it does not include these traditional corporate techniques. The ownership of the DA's tokens is all that is required for the holder to use the system. It's that simple. The value of the tokens is determined by how much people value the application. All the incentives, all the monetization, all the qys to raise capital are built into this beautifully simple structure. DAs are not required to recreate the functions that used to be necessary in centralized corporations in order to balance the power of shareholders and offer returns for investors and employees.

There are several characteristics that determine how decentralized applications can be classified. For the purposes of this paper, we will classify DAs based on whether they have their own block chain or they use the block chain of another DA. Based on this criterion, there are three types of DAs.

Type I decentralized applications have their own block chain. Bitcoin is the most famous example of a type I decentralized application, but Litecoin and other "alt-coins" are of the same type.

Type II decentralized applications use the block chain of a type I decentralized application. Type II decentralized applications are protocols and have tokens that are necessary for their function. The Master Protocol is an example of a type II decentralized application.

Type III decentralized applications use the protocol of a type II decentralized application. Type III decentralized applications are protocols and have tokens that are necessary for their function. A hypothetical Cloud Protocol that uses the Master Protocol to issue 'cloudcoins' that can be used to acquire cloud computing services would be an example of a type III decentralized application.

A useful analogy for a type I DA is a computer operating system (like Windows, Mac OS X, Linux, Android, iOS) for a type II DA a general purpose software program (like a word processor, a spreadsheet software, a file synchronization system such as Dropbox) and for type III DA, a specialized software solution (like a mail-merge tool that uses a word processor, an expense report macro that uses a spreadsheet, or a blogging platform that uses Dropbox.) Using this analogy, it may be expected that due to network effects and the ecosystem surrounding each decentralized application, there will be a few type I DAs, more type II DAs and even more type III DAs.

At this point, it is important to mention that there are currently several excellent open-source projects that leverage type I DAs. Colored coins and CoinJoin, for example, are based on the Bitcoin block chain and provide useful features to their users. These projects however cannot be classified as type II DAs, according to our definition, because they don't issue and manage a token. (The development and operation of these projects depends on donations instead.)

There are two common mechanism by which DAs can etablish consensus: the proof-of-work, POW, mechanism and the proof of stake, POS, mechanism.

With the proof-of-work mechanism, decisions about changes in a DA are made based on the amount of work that each stakeholder contributes to the operation of the DA. Bitcoin uses that approach for its day-to-day operation. The mechanism for establishing consensus through POW is commonly called mining.

With the proof-of-stake mechanism, decisions about changes in the DA are made based on the percent ownership that various stakeholders have over the application. For instance, the vote of a stakeholder who controls 10% of the tokens issued by a DA, carries a 10% weight. The Master Protocol is based on the POS mechanism.

The two mechanisms can be used in parallel, as is the case with Peercoin. Such a combination allows a DA to operate with less energy consumption than proof-of-work alone, and allows it to be more resistant to 51% attacks.

There are three common mechanisms by which DAs can distribute their tokens: mining, fundraising and development.

With the mining mechanism, tokens are distributed to those who contribute most work to the operation of a DA. Taking Bitcoin as an example, bitcoins are distributed through a predetermined algorithm to the miners that verify transactions and maintain the Bitcoin block chain.

With the fundraising mechanism, tokens are distributed to those who fund the initial development of the DA. Taking the Master Protocol as an example, Mastercoins were initially distributed to those who sent bitcoins to a given address at the rate of 100 Mastercoins per bitcoin sent. The bitcoins collected were then used to fund the development of applications that promoted the development of the Master Protocol.

WIth the development mechanism, tokens are generated using a predefined mechanism and are only available for the development of the DA. For example, in addition to its fundraising mechanism, the Master Protocol used the collaboration mechanism to fund its future development. An additional 10% of the Mastercoins generated through fundraising was set aside for development of the Master Protocol. Those Mastercoins become available through a pre-derminded schedule and are distributed via a community-driven bounty system where decisions are made based on the proof-of-stake mechanism.

To summarize: Tokens of a DA that establishes consensus through proof-of-work are distributed by mining, by people buying directly from miners and by trading for goods and services; that is the case with Bitcoin. Tokens of a DA that establishes consensus through proof-of-stake are distributed based on the contribution of stakeholders during a fundraiser, by people collaborating on the development of the DA and by trading for goods and services; that is the case with the Master Protocol.

Development of decentralized applications takes place in three steps.

Step 1: A whitepaper is published describing the DA and its features

As in the case of Bitcoin, the most common way by which a DA takes form is by the public release of a whitepaper that describes the protocol, its features, and its implementation. After the public release, feedback from the community is necessary for the further development of the DA.

Step 2: Initial tokens are distributed

If the DA is using the mining mechanism to distribute its tokens, a reference software program is released so that it can be used for mining. In the case of Bitcoin, a reference software program was released and the initial transaction block was created.

If the DA is using the fundraising mechanism, a wallet software becomes available to the stakeholders of the DA, so that they can exchange the tokens of the DA. In the case of Mastercoin, an Exodus fundraising address and a wallet script were publicly released.

If the DA is using the development mechanism, a bounty system is put in place that allows the suggestion of tasks to be performed, the tracking of the people who are working on those tasks and the criteria by which bounties can be awarded.

Step 3: The ownership stake of the DA is spread

As tokens from mining, fundraising and collaboration are distributed to a greater number of participants, the ownership of the DA becomes less and less centralized and participants that held a majority stake at earlier have less and less control. As the DA matures, participants with more diverse skills are incentivized to make valuable contributions, and the ownership of the DA is distributed further. Through market forces the tokens of a DA are transferred to those who value it the most. Those individuals then can contribute to the development of the DA in the areas that they have an expertise.

The case of Bitcoin illustrates the point. By some estimates, Satoshi Nakamoto mined many of the first 1,000,000 bitcoins. As developers contributed code to Bitcoin and miners contributed computational power to the Bitcoin network, the market began to value bitcoins more highly. As the system matured even more, people with diverse skills started valuing Bitcoin and contributing to its development. Now that more than 12 million bitcoins are in circulation and Satoshi Nakamoto's high original ownership stake has been diluted.

Operating under open-source licenses allows DAs to be open for innovation without restrictions of copyright or patent. In addition, by being completely open-source, decentralized applications can operate under the legal model of open-source software. Bitcoin, for example, uses the MIT open-source software license. The Master Protocol similarly, requires all code that is based on it to be open-source and available to the community.

One mechanism by which type II DAs can leverage the block chain of type I DAs is for type II DAs to embed additional data to the transactions taking place in the type I DA. The Master Protocol, for instance, embeds additional data on the transactions of the Bitcoin network. Although currently (February 2014) additional data are embedded in an ad hoc way into the Bitcoin block chain, the release of the 0.9 version of the Bitcoin reference client will provide a standard method for that embedding. By using the methodology of "provably prune-able outputs," type II decentralized applications that are based on Bitcoin will be able to embed data in a systematic way and Bitcoin miners will have the option to prune those data.

Given this development, several type III DAs are set to be developed. They include:

• cloudcoin, that provides Dropbox-like cloud storage of files,
• computecoin, that provides Amazon-Web-Services-like computing resources,
• meshcon, that provides mesh network-based Internet service,
• healthcoin, that provides insurance services and loss reimbursements,
• arbitrationcoin, that provides trust-less arbitration,
• AIcoin, that provides intelligent and automatic task execution.

DAs have the potential to become self-sustaining because they empower their stakeholders to invest in the development of the DA. Because of that, it is conceivable that DAs for payments, social networking, and cloud computing may one day surpass the valuation of multinational corporations like Western Union, Visa, Facebook, Google, and Amazon that are are currently active in the space.

It would be beneficial to have a well-grounded and easily accessible metaphor for DAs. Such a metaphor would ideally have the virtue of simplexity, so that it could be used for human-computer interfaces.

Such a metaphor could be a zygote. A zygote is the point where one biological cell generation ends and the next one begins. A zygote acclimates, and it responds to the outside world without changing its genes, it cannot be regulated, it is stuck with its own genes and its recursive. The zygote is autonomous because it is stuck with its own genes, it is an application because it is a cell, it is distributed, and it is authorized to act as a single entity from other other cells; it shares, in other words many of the characteristics of a decentralized application.

Terms that could created out of the term zygote include zyprotocol, the zygotic protocol, zapp, the zygotic application, zen, the zygotic entity, and zybit, the zygotic bit.