Academics and practitioners have not developed a unique definition for the term "DevOps."[a][b][c][d]
From an academic perspective, Len Bass, Ingo Weber, and Liming Zhu — three computer science researchers from the CSIRO and the Software Engineering Institute — suggested defining DevOps as "a set of practices intended to reduce the time between committing a change to a system and the change being placed into normal production, while ensuring high quality".
In 2009, the first conference named devopsdays was held in Ghent, Belgium. The conference was founded by Belgian consultant, project manager and agile practitioner Patrick Debois.[who?] The conference has now spread to other countries.
In 2012, the State of DevOps report was conceived and launched by Alanna Brown at Puppet.
As of 2014, the annual State of DevOps report was published by Nicole Forsgren, Gene Kim, Jez Humble and others.
In 2014, they found that DevOps adoption was accelerating.
Also in 2014, Lisa Crispin and Janet Gregory wrote the book More Agile Testing, containing a chapter on testing and DevOps.
As DevOps is intended to be a cross-functional mode of working, those that practice the methodology use different sets of tools—referred to as "toolchains"—rather than a single one. These toolchains are expected to fit into one or more of the following categories, reflective of key aspects of the development and delivery process:[unreliable source?][unreliable source?]
Agile and DevOps serve complementary roles: several standard DevOps practices such as automated build and test, continuous integration, and continuous delivery originated in the Agile world, which dates (informally) to the 1990s, and formally to 2001. Agile can be viewed as addressing communication gaps between customers and developers, while DevOps addresses gaps between developers and IT operations / infrastructure. Also, DevOps has focus on the deployment of developed software, whether it is developed via Agile or other methodologies..
ArchOps presents an extension for DevOps practice, starting from software architecture artifacts, instead of source code, for operation deployment.. ArchOps states that architectural models are first-class entities in software development, deployment, and operations.
TestOps is to hardware development what DevOps is to software development. The idea is a toolchain that links design and testoperations together. In the case of hardware, design means EDA tools and the CAD department, and test means electronic measurement equipment like oscilloscopes and so on.
Continuous delivery and DevOps have common goals and are often used in conjunction, but there are subtle differences.
While continuous delivery is focused on automating the processes in software delivery, DevOps also focuses on the organizational change to support great collaboration between the many functions involved.
DevOps and continuous delivery share a common background in agile methods and lean thinking: small and frequent changes with focused value to the end customer.[unreliable source?]Lean management and continuous delivery are fundamental to delivering value faster, in a sustainable way.
Continuous delivery focuses on making sure the software is always in a releasable state throughout its lifecycle. This makes it cheaper and less risky to deliver the software.
Improved collaboration and communication both between and within organizational teams can help achieve faster time to market, with reduced risks.
In 2003, Google developed site reliability engineering (SRE), an approach for releasing new features continuously into large-scale high-availability systems while maintaining high-quality end-user experience. While SRE predates the development of DevOps, they are generally viewed as being related to each other.[unreliable source?]
This section needs expansion. You can help by adding to it. (June 2018)
DevSecOps is an augmentation of DevOps to allow for security practices to be integrated into the DevOps approach. The traditional centralised security team model must adopt a federated model allowing each delivery team the ability to factor in the correct security controls into their DevOps practices.
IT performance can be measured in terms of throughput and stability. 
Throughput can be measured by deployment frequency and lead time for changes; stability can be measured by mean time to recover. The State of DevOps Reports found that investing in practices that increase these throughput and stability measures increase IT performance.
The goals of DevOps span the entire delivery pipeline. They include:
Faster mean time to recovery (in the event of a new release crashing or otherwise disabling the current system).
Simple processes become increasingly programmable and dynamic, using a DevOps approach.[unreliable source?] DevOps aims to maximize the predictability, efficiency, security, and maintainability of operational processes. Very often, automation supports this objective.
Practices that correlate with deployment frequency are:
Using version control for all production artifacts
Practices that correlate with a lead time for change are:
Using version control for all production artifacts
Practices that correlate with a mean time to recovery for change are:
Using version control for all production artifacts
Monitoring system and application health
Companies that practice DevOps[failed verification] have reported significant benefits, including: significantly shorter time to market, improved customer satisfaction, better product quality, more reliable releases, improved productivity and efficiency, and the increased ability to build the right product by fast experimentation.
The 2014 State of DevOps Report found that "IT performance strongly correlates with well-known DevOps practices such as the use of version
control and continuous delivery."
There is a lack of evidence in academic literature on the effectiveness of DevOps.[e]
DevOps initiatives can create cultural changes in companies  by transforming the way operations, developers, and testers collaborate during the development and delivery processes. Getting these groups to work cohesively is a critical challenge in enterprise DevOps adoption. DevOps is as much about culture, as it is about the toolchain.
Cattle not Pets: the paradigm of disposable server infrastructure.
10 deployments per day: the story of Flickr adopting DevOps.
Building a DevOps culture
Organizational culture is a strong predictor of IT and organizational performance. Cultural practices such as information flow, collaboration, shared responsibilities, learning from failures and new ideas are central to DevOps. Team-building and other employee engagement activities are often used to create an environment that fosters this communication and cultural change within an organization. Team–building activities can include board games, trust activities, and employee engagement seminars.[unreliable source?]
The 2015 State of DevOps Report discovered that the top seven measures with the strongest correlation to organizational culture are:
1. Organizational investment in DevOps:
2. Team leaders' experience and effectiveness.
3. Continuous delivery.
4. The ability of different disciplines (development, operations, and infosec) to achieve
5. Organizational performance.
6. Deployment pain.
7. Lean management practices.
To practice DevOps effectively, software applications have to meet a set of architecturally significant requirements (ASRs), such as: deployability, modifiability, testability, and monitorability. These ASRs require a high priority and cannot be traded off lightly.
Although in principle it is possible to practice DevOps with any architectural style, the microservices architectural style is becoming the standard for building continuously deployed systems. Small size service allows the architecture of an individual service to emerge through continuous refactoring, hence reducing the need for a big upfront design, allows for releasing the software early and continuously.
Some articles in the DevOps literature assume or recommend significant participation in DevOps initiatives from outside an organization's IT department, e.g.: "DevOps is just the agile principle, taken to the full enterprise."[unreliable source?]
In a survey published in January 2016 by the SaaS cloud-computing company RightScale, DevOps adoption increased from 66 percent in 2015 to 74 percent in 2016. And among larger enterprise organizations, DevOps adoption is even higher – 81 percent.[unreliable source?]
Adoption of DevOps is being driven by many factors – including:
^Dyck et. al (2015) "To our knowledge, there is no uniform definition for the terms release engineering and DevOps. As a consequence, many people use their own definitions or rely on others, which results in confusion about those terms."
^Jabbari et. al (2016) "The research results of this study showed the need for a definition as individual studies do not consistently define DevOps."
^Erich et. al (2017) "We noticed that there are various gaps in the study of DevOps: There is no consensus of what concepts DevOps covers, nor how DevOps is defined."
^Erich et. al (2017) "We discovered that there exists little agreement about the characteristics of DevOps in the academic literature."
^Erich et. al (2017) "We noticed that there are various gaps in the study of DevOps: [...] There is a lack of evidence on the effectiveness of DevOps.
^Dyck, Andrej; Penners, Ralf; Lichter, Horst (19 May 2015). "Towards Definitions for Release Engineering and DevOps". Proceedings of the 2015 IEEE/ACM 3rd International Workshop on Release Engineering. IEEE.
^Jabbari, Ramtin; bin Ali, Nauman; Petersen, Kai; Tanveer, Binish (May 2016). "What is DevOps?: A Systematic Mapping Study on Definitions and Practices". Proceedings of the 2016 Scientific Workshop. Association for Computing Machinery.
^ abcErich, F.M.A.; Amrit, C.; Daneva, M. (June 2017). "A Qualitative Study of DevOps Usage in Practice". Journal of Software: Evolution and Process. 29 (6).
Davis, Jennifer; Daniels, Ryn (30 May 2016). Effective DevOps : building a culture of collaboration, affinity, and tooling at scale. Sebastopol, CA: O'Reilly. ISBN9781491926437. OCLC951434424.
Kim, Gene; Debois, Patrick; Willis, John; Humble, Jez; Allspaw, John (7 October 2015). The DevOps handbook : how to create world-class agility, reliability, and security in technology organizations (First ed.). Portland, OR. ISBN9781942788003. OCLC907166314.
Forsgren, Nicole; Humble, Jez; Kim, Gene (27 March 2018). Accelerate: The Science of Lean Software and DevOps: Building and Scaling High Performing Technology Organizations (First ed.). IT Revolution Press. ISBN9781942788331.