> uBlock comes in two sibling flavors: this project, and [uBlock Origin](https://github.com/gorhill/uBlock).
> With slightly different feature sets curated for people's unique preferences — but the**same astounding performance.** Both are free, open-source, and share the contributions of many.
uBlock blocks ads through its support of the [Adblock Plus filter syntax](https://adblockplus.org/en/filters). uBlock [extends](https://github.com/chrisaljoudi/uBlock/wiki/Filter-syntax-extensions) the syntax and is designed to work with custom rules and filters.
* **Safari**: available to install [from the homepage](https://chrismatic.io/ublock/safari/), or from the [Safari Extension Gallery](https://extensions.apple.com/details/?id=net.gorhill.uBlock-96G4BAKDQ9).
* **Chrome**: available on the [Chrome Web Store](https://chrome.google.com/webstore/detail/ublock/epcnnfbjfcgphgdmggkamkmgojdagdnn) or for [manual](https://github.com/chrisaljoudi/uBlock/tree/master/dist#install) installation.
* **Opera**: available on the [Opera Store](https://addons.opera.com/en-gb/extensions/details/ublock/).
* **Firefox**: available on the [Firefox Add-ons homepage](https://addons.mozilla.org/en-US/firefox/addon/ublock/), or for [manual](https://github.com/chrisaljoudi/uBlock/releases) installation.
<sup>[1] Details of the benchmark available at <ahref="https://github.com/chrisaljoudi/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/chrisaljoudi/uBlock/blob/master/doc/benchmarks/cpu-usage-overall-20141226.ods">this LibreOffice spreadsheet</a>.</sup>
* **To benefit from uBlock's higher efficiency,** it's advised that you don't use other inefficient blockers at the same time (such as AdBlock or Adblock Plus). uBlock will do [as well or better](#blocking) than most popular ad blockers.
* It's important to note that blocking ads [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.
* _EasyList_, _Peter Lowe's Adservers_, _EasyPrivacy_ and _Malware domains_ are enabled by default when you install uBlock. Many more lists are readily available to block trackers, analytics, and more. Hosts files are also supported.
* Once you install uBlock, you can easily un-select any of the pre-selected filter lists if you think uBlock blocks too much. For reference, Adblock Plus installs with only _EasyList_ enabled by default.