Online dispute resolution (ODR) is a form of dispute resolution which uses technology to facilitate the resolution of disputes between parties. It primarily involves negotiation, mediation or arbitration, or a combination of all three. In this respect it is often seen as being the online equivalent of alternative dispute resolution (ADR). However, ODR can also augment these traditional means of resolving disputes by applying innovative techniques and online technologies to the process.

ODR is a wide field, which may be applied to a range of disputes; from interpersonal disputes including consumer to consumer disputes (C2C) or marital separation; to court disputes and interstate conflicts. It is believed that efficient mechanisms to resolve online disputes will impact in the development of e-commerce. While the application of ODR is not limited to disputes arising out of business to consumer (B2C) online transactions, it seems to be particularly apt for these disputes, since it is logical to use the same medium (the internet) for the resolution of e-commerce disputes when parties are frequently located far from one another. Designing an appropriate ODR system requires attention to the interests of both consumers and companies as well as a deep understanding of the requirements of procedural justice.

Dispute resolution techniques range from methods where parties have full control of the procedure, to methods where a third party is in control of both the process and the outcome. These primary methods of resolving disputes may be complemented with Information and Communication Technology (ICT). When the process is conducted mainly online it is referred to as ODR, i.e. to carry out most of the dispute resolution procedure online, including the initial filing, the neutral appointment, evidentiary processes, oral hearings if needed, online discussions, and even the rendering of binding settlements. Thus, ODR is a different medium to resolve disputes, from beginning to end, respecting due process principles.

ODR was born from the synergy between ADR and ICT, as a method for resolving disputes that were arising online, and for which traditional means of dispute resolution were inefficient or unavailable. The introduction of ICT in dispute resolution is currently growing to the extent that the difference between off-line dispute resolution and ODR is blurry. It has been observed that it is only possible to distinguish between proceedings that rely heavily on online technology and proceedings that do not. Some commentators have defined ODR exclusively as the use of ADR assisted principally with ICT tools. Although part of the doctrine incorporates a broader approach including online litigation and other sui generis forms of dispute resolution when they are assisted largely by ICT tools designed ad hoc. The latter definition seems more appropriate since it incorporates all methods used to resolve disputes that are conducted mainly through the use of ICT. Moreover, this concept is more consistent with the fact that ODR was born from the distinction with off-line dispute resolution processes.

In ODR, the information management is not only carried out by physical persons but also by computers and software. The assistance of ICT has been named by Katsh and Rifkin as the 'fourth party' because ODR is seen as an independent input to the management of the dispute. In addition to the two (or more) disputants and the third neutral party, the labelling of technology as the fourth party is a clear metaphor which stresses how technology can be as powerful as to change the traditional three side model. The fourth party embodies a range of capabilities in the same manner that the third party does. While the fourth party may at times take the place of the third party, i.e. automated negotiation, it will frequently be used by the third party as a tool for assisting the process.

The fourth party may do many things such as organize information, send automatic responses, shape writing communications in a more polite and constructive manner e.g. blocking foul language. In addition, it can monitor performance, schedule meetings, clarify interests and priorities, and so on. The assistance of the fourth party will increase the more technology advances, thus reducing the role of the third neutral party. It has been predicted that virtual "fourth party" avatars will be created to judge disputes and could become more skilled and intelligent over time. Katsh and Wing argue that ICT advance is occurring exponentially since ICT advance speeds up over the time. As a result, ODR processes are increasing in efficiency providing their disputants with greater advantages in terms of time saving and cost reductions.

In practice it is difficult to provide a self-contained definition of ODR, and given the pace of change it may not even be possible to do so. The use of technology usually involves the use of Internet-based communications technology at some stage, but ODR does not necessarily involve purely online processes – further, many could be replicated offline using pen and paper, or could be achieved using computers without Internet connections.

The range of terms and acronyms used to describe the field augments the confusion often felt by those unfamiliar with the new field of ODR. These terms include: