Digital engineering is defined as ‘‘an integrated digital approach that uses authoritative sources of systems’ data and models as a continuum across disciplines to support lifecycle activities from concept through disposal .’’
Digital Engineering (DE) is DoD’s initiative that combines model-based techniques, digital practices, and computing infrastructure to enable delivery of high pay-off solutions to the warfighter at the speed of relevance. DE modernizes how the DoD conceives, designs, operates, and sustains capabilities to outpace its adversaries. By shaping the culture and workforce to collaborate and work more efficiently with an authoritative source of truth, DE incorporates technological innovation into an integrated digital model-based approach to transform the state of engineering practice in support lifecycle activities.
In June 2018, Dr. Michael Griffin, the Under Secretary of Defense for Research and Engineering, released the DoD Digital Engineering Strategy . The DoD Digital Engineering Strategy outlines five strategic goals for this engineering transformation. The strategy encourages innovation in the way we conceive, build, test, field, and sustain our national defense systems, and how we must train and shape the workforce to use digital engineering practices.
Goal 1 Formalize the development, integration, and use of models to inform enterprise and program decision making 
The first goal establishes the formal planning, development, and use of models as an integral part of performing engineering activities. Digital engineering extends beyond traditional model-based approaches that typically focus on a particular activity or aspect (e.g., model-based design, digital model-based manufacturing, model-based testing, model-based manufacturing, model-based X) of the lifecycle. For MBSE, the focus is on formal systems modeling across the lifecycle. The vision for digital engineering is to encompass the broad spectrum of models as a continuum across the lifecycle.
Goal 2 Provide an enduring, authoritative source of truth 
This goal moves the primary means of communication from documents to digital models and data. This enables access, management, analysis, use, and distribution of information from a common set of digital models and data. As a result, authorized stakeholders have the current, authoritative, and consistent information for use over the lifecycle.
Goal 3 Incorporate technological innovation to improve the engineering practice 
This goal extends beyond the traditional model-based approaches to incorporate advancements in technology and practice. Digital engineering approaches also support rapid implementation of innovations within a connected digital end-to-end enterprise.
Goal 4 Establish a supporting infrastructure and environment to perform activities, collaborate, and communicate across stakeholders 
This goal promotes the establishment of robust infrastructure and environments to support the digital engineering goals. It incorporates an information technology (IT) infrastructure and advanced methods, processes, and tools, as well as collaborative trusted systems that enforce protection of intellectual property, cybersecurity, and security classification.
Goal 5 Transform the culture and workforce to adopt and support digital engineering across the life cycle 
The final goal incorporates best practices of change management and strategic communications to transform the culture and workforce. Focused efforts are needed to lead and execute the change, and support the organization’s transition to digital engineering.
“Advancements in computing, modeling, data management, and analytical capabilities offer great opportunities for the engineering practice. Applying these tools and methods, we are shifting toward a dynamic digital engineering ecosystem. This digital engineering transformation is necessary to meet new threats, maintain overmatch, and leverage technology advancements .” – Kristen Baldwin - Acting Deputy Assistant Secretary of Defense for Systems Engineering (DASD(SE)
“Digital Engineering is the fundamental component to enable the U.S. Air Force to rapidly make informed decisions to facilitate agile acquisition and Rapid fielding of dominant weapon systems for the warfighter .” – Mr. Jeff Stanley Deputy Assistant Secretary of the Air Force for Science, Technology, and Engineering, Office of the Assistant Secretary of the Air Force for Acquisition and Logistics
“Rapidly evolving threats, warfighting concepts, and technologies require us to innovate, engineer, and integrate quickly. Authoritative and accessible data, models, and architectures must underpin modernization .” – COL Robert H. Kewley Jr. Acting Executive Director, Office of the Chief Systems Engineer HQDA Assistant Secretary of the Army (Acquisition, Logistics and Technology) (ASA(ALT))
“Digital engineering approaches and methods are a key enabler to delivery of affordable capability to the warfighter with speed and lethality. The Department of the Navy has proactively embraced digital engineering and believes it is the way we must execute business in the 21st century .” – Mr. William Bray Deputy Assistant Secretary of the Navy for Research, Development, Test and Evaluation (DASN(RDT&E))
Digital Transformation  on the CIO website describes the topic as follows:
Model-based Engineering in a report by National Institute of Standards and Technology (NIST) describes the topic as follows:
Digital Twin on the Smarter with Gartner website describes the topic as follows:
Digital Thread presented by Dr. Ed Kraft to the NIST MBE Summit in 2013 describes the topic as follows:
 Office of the Deputy Assistant Secretary of Defense (Systems Engineering) [ODASD (SE), “DAU Glossary: Digital Engineering,” Defense Acquisition University (DAU), 2017. [Online]. Available: https://www.dau.mil/glossary/pages/3626.aspx. [Accessed 6 November 2018].
 Office ot the Deputy Assistant Secretary of Defense for Systems Engineering, “Digital Engineering Strategy,” Department of Defense, Washington, DC, 2018.
 M. Eckstein, “Aegis Combat System ‘Virtual Twin’ Pilot Program Could Lead to Fielding Faster Upgrades,” U. S. Naval Institute (USNI), 6 December 2016. [Online]. Available: https://news.usni.org/2017/12/06/aegis-combat-system-virtual-twin-pilot-program-lead-fielding-faster-upgrades. [Accessed 6 November 2018].
 Naval Air Warfare Center Aircraft Division (NAWCAD), “Systems Engineering Transformation,” Youtube, 30 Januarary 2018. [Online]. Available: https://www.youtube.com/watch?v=171blNCgpCo. [Accessed 6 November 2018].
 Massachusetts Institute of Technology (MIT), “How the U.S. Naval Air Systems Command is transforming its engineering workforce with MIT’s Architecture and Systems Engineering Online Program,” 2018. [Online]. Available: https://sysengonline.mit.edu/wp-content/uploads/2018/08/NAVAIR-Article-2018.pdf. [Accessed 6 November 2018].
 V. Insinna, “The US Air Force’s top acquisition exec talks hypersonic prototypes and more,” 30 July 2018. [Online]. Available: https://www.defensenews.com/digital-show-dailies/farnborough/2018/07/27/the-us-air-forces-top-acquisition-exec-talks-hypersonic-prototypes-and-more/. [Accessed 6 November 2018].
 G. Evans, “Naval Technology: The digital naval shipyard,” 12 February 2018. [Online]. Available: https://www.naval-technology.com/features/digital-naval-shipyard/. [Accessed 6 November 2018].  D. Bonnet and P. Michelman, “What Digital Transformation Means in 2018 and Beyond on Youtube,” MIT Sloan Management Review Webinar, 22 August 2018. [Online]. Available: https://youtu.be/gqy70cDPwRY. [Accessed 12 November 2018].
 B. Schmarzo , “CIO IDG: What is Digital Transformation?,” IDG Communications, Inc., 31 May 2017. [Online]. Available: https://www.cio.com/article/3199030/analytics/what-is-digital-transformation.html. [Accessed 12 November 2018].
 J. Lubell, K. Chen, S. Frechette, J. Horst and P. Huang, “NIST Technical Note 1753: Model Based Enterprise / Technical Data Package Summit Report,” August 2012. [Online]. Available: https://nvlpubs.nist.gov/nistpubs/TechnicalNotes/NIST.TN.1753.pdf. [Accessed 12 November 2018].
 P. Christy, “Smarter with Gartner: Prepare for the Impact of Digital Twins,” Gartner, 18 September 2017. [Online]. Available: https://www.gartner.com/smarterwithgartner/prepare-for-the-impact-of-digital-twins/. [Accessed 6 November 2018].
 E. Kraft, “NIST MBE Summit 2013: Expanding the Digital to Impact Total Ownership Cost,” 18 December 2013. [Online]. Available: https://www.nist.gov/sites/default/files/documents/el/msid/1Kraft_DigitalThread.pdf. [Accessed 2018 November 2018].
 M. A. Bone, M. R. Blackburn, D. H. Rhodes, D. N. Cohen and J. A. Guerrero, “Transforming systems engineering through digital engineering,” The Journal of Defense Modeling and Simulation., 2018.
 K. . J. Baldwin, “Model-Based Systems Engineering: Enabling the Digital Engineering Practice in the Department of Defense, Getting It Right: T,” The Quarterly Newsletter of Mission Assurance, pp. 1-3, 2017.
 NDIA Systems Engineering Division M&S Committee, “Final Report of the Model Based Engineering (MBE) Subcommittee,” National Defense Industrial Association (NDIA), Arlington, VA, 2011.
 Systems Engineering Vision 2025 Project Team of INCOSE, “A World in Motion - Systems Engineering Vision 2025,” International Council of Systems Engineering (INCOSE), San Diego, CA, 2014.
 ODASD of Systems Engneering, “Digital Engineering,” Department of Defense, 9 July 2018. [Online]. Available: http://www.acq.osd.mil/se/initiatives/init_de.html. [Accessed 6 November 2018].
 M. Cotteleer, . J. Schibi and J. Holdowsky, “Following the Digital Thread: How the Digital Thread Weaves Its Way Through the Business,” MIT Sloan Management Review Webinars, 08 March 2018. [Online]. Available: https://sloanreview.mit.edu/video/following-the-digital-thread-how-the-digital-thread-weaves-its-way-through-the-business/. [Accessed 12 November 2018].