The current reality is that there are *two branches*, not an official one and a lesser one. I keep developing my branch the same way and in the same spirit I have since [the beginning of uBlock in June 23, 2014](http://www.wilderssecurity.com/threads/ublock-a-lean-and-fast-blocker.365273/).
You are more likely than anywhere else to find a neutral explanation in this [Wikipedia article](http://en.wikipedia.org/wiki/UBlock) for the differences in features between uBlock Origin and uBlock.
uBlock Origin (or uBlock₀) is not an *ad blocker*; it's a general-purpose blocker. uBlock₀ blocks ads through its support of the [Adblock Plus filter syntax](https://adblockplus.org/en/filters). uBlock₀ [extends](https://github.com/gorhill/uBlock/wiki/Filter-syntax-extensions) the syntax and is designed to work with custom rules and filters.
That said, it's important to note that using a blocker is **NOT** [theft](https://twitter.com/LeaVerou/status/518154828166725632). Don't fall for this creepy idea. The _ultimate_ logical consequence of `blocking = theft` is the criminalisation of the inalienable right to privacy.
Ads, "unintrusive" or not, are just the visible portions of privacy-invading apparatus entering your browser when you visit most sites nowadays. **uBlock₀'s main goal is to help users neutralize such privacy-invading apparatus** — in a way that welcomes those users who don't wish to use more technical, involved means (such as [µMatrix](https://github.com/gorhill/uMatrix)).
_EasyList_, _Peter Lowe's Adservers_, _EasyPrivacy_ and _Malware domains_ are enabled by default when you install uBlock₀. Many more lists are readily available to block trackers, analytics, and more. Hosts files are also supported.
Once you install uBlock₀, you may easily un-select any of the pre-selected filter lists if you think uBlock₀ blocks too much. For reference, Adblock Plus installs with only _EasyList_ enabled by default.
For advanced usage, read about [dynamic filtering](https://github.com/gorhill/uBlock/wiki/Dynamic-filtering:-quick-guide) and more on [uBlock₀'s wiki](https://github.com/gorhill/uBlock/wiki).
<sup>[1] Details of the benchmark available at <ahref="https://github.com/gorhill/uBlock/wiki/Firefox-version:-benchmarking-memory-footprint">Firefox version: benchmarking memory footprint</a>.</sup><br>
<sup>[2] Important note: There is currently a [bug in Chromium 39+ which causes a new memory leak each time the popup UI of an extension is opened](https://code.google.com/p/chromium/issues/detail?id=441500). This affects <i>all</i> extensions. Keep this in mind when measuring Chromium's memory usage. In the benchmarks, I avoided opening the popups completely.</sup><br>
<sup>Details of the benchmark available in <ahref="https://github.com/gorhill/uBlock/blob/master/doc/benchmarks/cpu-usage-overall-20141226.ods">this LibreOffice spreadsheet</a>.</sup>
You can install the latest version [manually](https://github.com/gorhill/uBlock/tree/master/dist#install), from the [Chrome Store](https://chrome.google.com/webstore/detail/ublock-origin/cjpalhdlnbpafiamejdnhcphjbkeiagm), or from the [Opera store](https://addons.opera.com/en-gb/extensions/details/ublock/).
Alternatively, you can install [chrisaljoudi/uBlock](https://github.com/chrisaljoudi/uBlock) from [Chrome store](https://chrome.google.com/webstore/detail/ublock/epcnnfbjfcgphgdmggkamkmgojdagdnn). Slightly different feature set, same performance.
[Firefox Add-ons web site](https://addons.mozilla.org/firefox/addon/ublock-origin/), or install manually by downloading the latest [uBlock0.firefox.xpi](https://github.com/gorhill/uBlock/releases) file, and by dragging the downloaded `xpi` file to your add-on page.
Alternatively, you can install [chrisaljoudi/uBlock](https://github.com/chrisaljoudi/uBlock) from [Firefox Add-ons homepage](https://addons.mozilla.org/firefox/addon/ublock/). Slightly different feature set, same performance, proper support for legacy Firefox-based browsers.
To benefit from uBlock Origin's higher efficiency, it's advised that you don't use other inefficient blockers at the same time (such as AdBlock or Adblock Plus). uBlock₀ will do [as well or better](#blocking) than most popular ad blockers.
