• CL: "Change List", a set of changes to files (akin to a single git commit).
  • CQ: "Commit Queue", infrastructure to automatically check/build/test/verify/etc... CLs before merging into the tree. See also the Chromium CQ and Chromium OS CQ pages.
  • CRX file: CRX files are ZIP files with a special header and the .crx file extension used to package Extensions and Apps.
  • DUT: "Device under test", used to refer to the system running Chromium [OS] and where tests are being executed.
  • GTTF: "Green Tree Task Force"
  • LGTM: "Looks good to me", commonly used to approve a code review.
  • LKCR: "Last known compilable revision" - similar to LKGR (below), the last build that compiled.
  • LKGM: "Last known good manifest", the last manifest version that passed a minimal set of tests.
  • MVP: "Minimum viable product", used to refer to the subset of a feature we want to ship initially.
  • PFQ: "Preflight queue", used to describe bot configurations in the waterfall that run to test/gate changes before they're allowed into the tree for everyone to see. See also the PFQ FAQ.
  • PTAL: "Please take a[nother] look", often used when someone is happy with the state of a CL and want reviewers to look [again].
  • RSLGTM: "Rubber stamp looks good to me", used when the reviewer is merely granting OWNERS approval without doing a proper code review.
  • SGTM: Secret Google Time Machine "Sounds good to me"
  • TBR: "To be reviewed". In specific circumstances used to land code and have it reviewed later.
  • ToT: "Tip of Tree", as in the latest revision of the source tree.
  • TPM: "Trusted Platform Module", Tamper-resistant chip that the CPU can talk to. Securely stores keys and does cryptographic ops. We use this to encrypt the keys used to encrypt user files (to make passphrase recovery more difficult). See also TpmQuickRef.
  • WAI: "Working As Intended", e.g. the behavior described is not a bug, but working as it is supposed to. This is not to say the intention cannot change (as a feature request), simply that it is not a bug.
  • WIP: "Work In Progress" - e.g. a patch that's not finished, but may be worth an early look

English Acronyms and Abbreviations

  • AFAICT: as far as I can tell
  • AFAIK: as far as I know
  • e.g.: (latin) for example
  • FWIW: for what it's worth
  • IANAL: I am not a lawyer
  • IIRC: if I recall/remember correctly
  • IIUC: if I understand correctly
  • IMO: in my opinion
  • IMHO: in my honest opinion
  • IOW: in other words
  • i.e.: (latin) in other words
  • nit: short for "nitpick"; refers to a trivial suggestion such as style issues
  • PSA: public service announcement
  • WRT: with respect to

Chrome Concepts

  • Chrome Component: Components of chrome that can be updated independently from Chrome its self. Examples are PDF Viewer, Flash Plugin.
  • Component App / Component Extension: App or Extension built and shipped with Chrome. Examples are Bookmark Manager, File manager.
  • Default Apps: Apps or Extensions that are shipped with Chrome as .CRX files and installed on first run.
  • Extension: Third party developed code that modifies the browser.
  • Packaged App: Packaged apps run outside of the browser, are built using web technologies and privileged APIs.
  • Packaged App (old): Older packaged apps (pre 2013) still ran in tabs, but with offline packaged resources.
  • Shared Modules: Extensions or Apps that export resources accessible from other Ext/Apps. Dependencies are installed automatically.
  • Aura: The unified graphics compositor (docs).
  • Ash: The Aura shell (e.g. the Chromium OS look); see Aura for more info.


  • buildbot: A column in the build waterfall, or the slave (machine) connected to that column, or the build waterfall infrastructure as a whole.
  • clobber: To delete your build output directory.
  • component build: A shared library / DLL build, not a static library build.
  • land: Landing a patch means to commit it.
  • slave: A machine connected to the buildbot master, running a sequence of build and test steps.
  • tryserver: A machine that runs a subset of all tests on all platforms.
  • sheriff: The person currently charged with watching over the build waterfall to make sure it stays green (not failing). There are usually two sheriffs at one time. The current sheriffs can be seen in the upper left corner of the waterfall page.
  • symbolication: The process of resolving stack addresses and backtraces to human readable source code methods/lines/etc...
  • tree: This means the source tree in subversion. Often used in the context of "the tree is closed" meaning commits are currently disallowed.
  • try: To try a patch means to submit it to the tryserver before committing.
  • waterfall: The page showing the status of all the buildbots.


  • Flakiness: Intermittent test failures (including crashes and hangs), often caused by a poorly written test.
  • Jank/Jankiness: User-perceptible UI lag.
  • Chumping: Bypassing the CQ and committing your change directly to the tree. Generally frowned upon as it means automatic testing was bypassed before the CL hits developer systems.

User Interface

  • Bookmark bubble: A "modal" bubble that appears when the user adds a bookmark allowing them to edit properties or cancel the addition.
  • Download bar: The bar that appears at the bottom of the browser during or after a file has been downloaded.
  • Extensions bar: Similar to the download bar, appears at the bottom of the screen when the user has installed an extension.
  • Infobar: The thing that drops down below asking if you want to save a password, did you mean to go to another URL, etc.
  • NTB: New Tab button (the button in the tab strip for creating a new tab)
  • NTP or NNTP: The New Tab Page, or the freshly rebuilt new tab functionality dubbed New New Tab Page.
  • Status bubble: The transient bubble at the bottom left that appears when you hover over a url or a site is loading.


  • channels: The number of audio channels present. We use "mono" to refer to 1 channel, "stereo" to refer to 2 channels, and "multichannel" to refer to 3+ channels.
  • clicking: Audio artifacts caused by bad/corrupted samples.
  • corruption: Visible video decoding artifacts. Usually a result of decoder error or seeking without fully flushing decoder state. Looks similar to this.
  • FFmpeg: The open source library Chromium uses for decoding audio and video files.
  • sample: A single uncompressed audio unit. Changes depending on the format but is typically a signed 16-bit integer.
  • sample bits: The number of bits per audio sample. Typical values are 8, 16, 24 or 32.
  • sample rate: The number of audio samples per second. Typical values for compressed audio formats (AAC/MP3/Vorbis) are 44.1 kHz or 48 kHz.
  • stuttering: Short video or audio pauses. Makes the playback look/sound jerky, and is often caused by insufficient data or processor.
  • sync: Audio/video synchronization.

Toolchain (compiler/debugger/linker/etc...)

  • ASan, LSan, MSan, TSan: AddressSanitizer, LeakSanitizer, MemorySanitizer and ThreadSanitizer, bug detection tools used in Chromium testing. ASan detects addressability issues (buffer overflow, use after free etc), LSan detects memory leaks, MSan detects use of uninitialized memory and TSan detects data races.
  • AFDO: Automatic FDO; see FDO & PGO.
  • FDO: Feedback-Directed Optimization; see AFDO & PGO.
  • fission: A new system for speeding up processing of debug information when using GCC; see this page for more details.
  • gold: The GNU linker; a newer/faster open source linker written in C++ and supporting threading.
  • ICE: Internal Compiler Error; something really bad happened and you should file a bug.
  • PGO: Profile Guided Optimization; see AFDO & FDO.

Chromium OS

  • board: The name of the system you're building Chromium OS for; see the official Chrome OS device list for examples.
  • devserver: System for updating packages on a Chromium OS device without having to use a USB stick or doing a full reimage. See the Dev Server page.
  • powerwash: Wiping of the stateful partition (system & all users) to get a device back into a pristine state. The TPM is not cleared, and Lockbox is kept intact (thus it is not the same as a factory reset). See the Powerwash design doc.