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ROOT Logo.png
CMS ROOT plot.png
The CMS experiments presented on July 4, 2012, the status of the Standard Model Higgs search. All the plots presented that day were done using ROOT.
Original author(s)René Brun, Fons Rademakers [1]
Stable release
6.26/00 / March 3, 2022; 2 months ago (2022-03-03)
Written inC++
Operating systemMicrosoft Windows, OS X, Linux, Solaris, IBM AIX
PlatformIA-32, x86-64
Size86–327 MB
TypeData analysis, Plotting

ROOT is an object-oriented program and library developed by CERN. It was originally designed for particle physics data analysis and contains several features specific to this field, but it is also used in other applications such as astronomy and data mining. The latest minor release is 6.26, as of 2022-03-08.[3]


CERN maintained a program library written in FORTRAN for many years; development and maintenance were discontinued in 2003 in favour of ROOT, written in C++. ROOT development was initiated by René Brun and Fons Rademakers in 1994. Some parts are published under the LGPL, and others are based on GPL software and thus are also published under the terms of the GPL. It provides platform independent access to a computer's graphics subsystem and operating system using abstract layers. Parts of the abstract platform are: a graphical user interface and a GUI builder, container classes, reflection, a C++ script and command line interpreter (CINT in version 5, cling in version 6), object serialization and persistence.

The packages provided by ROOT include those for

The ATLAS experiments presented on 4 July 2012 the status of the Standard Model Higgs search. All the plots presented that day were created in ROOT.

A key feature of ROOT is a data container called tree, with its substructures branches and leaves. A tree can be seen as a sliding window to the raw data, as stored in a file. Data from the next entry in the file can be retrieved by advancing the index in the tree. This avoids memory allocation problems associated with object creation, and allows the tree to act as a lightweight container while handling buffering invisibly.

ROOT is designed for high computing efficiency, as it is required to process data from the Large Hadron Collider's experiments estimated at several petabytes per year. As of 2009 ROOT is mainly used in data analysis and data acquisition in particle physics (high energy physics) experiments, and most current experimental plots and results in those subfields are obtained using ROOT.

The inclusion of a C++ interpreter (CINT until version 5.34, Cling from version 6.00) makes this package very versatile as it can be used in interactive, scripted and compiled modes in a manner similar to commercial products like MATLAB.

On July 4, 2012 the ATLAS and CMS LHC's experiments presented the status of the Standard Model Higgs search. All the plots presented that day were done using ROOT.


Criticisms of ROOT include its difficulty for beginners, as well as various aspects of its design and implementation. Frequent causes of frustration include extreme code bloat, heavy use of global variables,[4] and an overcomplicated class hierarchy. From time to time these issues are discussed on the ROOT users mailing list.[5][6] While scientists dissatisfied with ROOT have in the past managed to work around its flaws,[7] some of the shortcomings are regularly addressed by the ROOT team. The CINT interpreter, for example, has been replaced by the Cling interpreter,[8] and numerous bugs are fixed with every release.

Applications of ROOT[edit]

Several particle physics collaborations have written software based on ROOT, often in favor of using more generic solutions (e.g. using ROOT containers instead of STL).

See also[edit]


  1. ^ "Project Founders". Retrieved 2019-06-19.
  2. ^ "ROOT Team". Retrieved 2022-02-10.
  3. ^ "Installing ROOT - ROOT". Retrieved 2022-03-08.
  4. ^ Buckley, Andy (2007-08-27). "The problem with ROOT (a.k.a. The ROOT of all Evil)". InsectNation. Retrieved 3 May 2016.
  5. ^ "Re: Wikipedia criticism about root". Retrieved 3 May 2016.
  6. ^ "RE: Re: Wikipedia criticism about root". Retrieved 3 May 2016.
  7. ^ "What is ROOT?". 1 June 2009. Retrieved 3 May 2016.
  8. ^ "ROOT Version 6.06 Release Notes". 2 June 2015. Retrieved 3 May 2016.

External links[edit]