Web Browsers Web Browsers and their 'Add-ons' / 'Extensions'

Definition of ‘Web browser’ ▪A Web browser is a computer program used for accessing sites or information on a network (such as the World Wide Web). ▪The main reason a person utilizes a browser is to view Web pages on the Internet. ▪The browser application: ▪retrieves or fetches code, usually written in HTML (HyperText Markup Language) and/or another language, from a webserver, ▪interprets this code, and ▪renders (displays) it as a Web page for you to view. Source:

For example, it will read this:

… and then display it as this:

But a browser can also be used: ▪for accessing other equipment on the network, such as my modem / router ▪If I enter the address in the address bar, I can access and change my router settings:

Browser ranking by features Source:

Browser ranking by usage (Desktop & tablet browsers) BrowserMarch 2015March 2016changerelative IE (all)17.88%12.54%-5.34%-29.90% Edge1.98% Chrome49.07%56.51%+7.44%+15.20% Firefox16.81%14.29%-2.52%-15.00% Safari10.93%9.42%-1.51%-13.80% Opera1.62%1.87%+0.25%+15.40% Others3.69%5.37%+1.68%+45.50% Source: Statistics for mobile browsers are also available from the same source

Browser engines ▪Each browser uses a web browser engine (also known as a layout engine or rendering engine), which does most of the work. ▪Liken it to a car engine: a single engine type may be fitted into multiple cars, but each of those cars may have a different body style, dashboard layout, and generally look completely different from one another. ▪Engines timeline: Mozilla Firefox Microsoft Internet Explorer Google Chrome ▪Multi-process: Most browser engines are now ‘multi-process’. Firefox is still ‘single-process’, thus making it slower, but it is currently changing to running ‘multi-process’. Source:

Cookies ▪What are cookies? ▪Cookies are text files containing small pieces of information that the particular web site sends to your browser. Your browser stores and saves these cookies on your computer (usually in your Temporary Internet files folder). (Not all web sites use cookies.) ▪Two types of cookies: ▪Session cookies (or Transient cookies) stay on a user’s computer only for that browsing session. They are deleted when the user closes the browser. ▪Persistent cookies remain on a user’s devices indefinitely, or until a pre-set expiry date, or until deleted (and thus can be used to track a user’s browsing history over time). ▪Two sources of cookies: ▪First-party cookies belong only to the site you are visiting, and relay information directly back to that site ▪Third-party cookies belong to other services other than the site being visited, and relay information back to those third-party services. These may be used to help, say, Google tailor your subsequent web browsing experience based on your preferences, such as placing advertisements tailored to your browsing history. Since the same third-party cookie can appear on many different websites that a user visits, they can be used to track a user’s browsing history across many different services. Sources:

What information do Cookies store? ▪Persistent cookies ▪Browsing preferences : If the web site permits some customisation, then your preferences may be stored in cookies, so that your choices do not have to be reset on your next visit. E.g. If you want a weather web site to default to showing you the weather for Slinfold, then that will be stored in a cookie. ▪Registration details : If you have registered with the web site, it may store some or all of your registration details to save you completing the details on each visit. ▪Record of visits : Some websites allow you a specified number of free visits before you have to register / pay. ▪Session cookies ▪Pages visited : Some web sites may track pages visited during the current session for navigation purposes. ▪Form entry data : If you are completing a multi-page form, the data entered may temporarily be stored in cookies so that it remains available when changing pages, and/or because it may determine which pages / questions should be visited or skipped subsequently. ▪Shopping cart : The web site needs to store information about items you have placed in your ‘shopping cart’ ready for when you check out. Sources:

Are Cookies dangerous? ▪Are cookies dangerous? ▪Cookies are simple text files and thus, in and of themselves, are completely harmless: text files cannot execute programs or carry out tasks. ▪However, some Web sites use them to track users as they browse the Web, collecting highly personal information and often surreptitiously transferring that information to other Web sites without permission or warning. ▪Can cookies be used to spy on me? ▪Again, because they are simple text files, they cannot be used to view data on your hard disk, or capture other information from your computer. ▪Why are cookies controversial? ▪Many online advertisement companies attach cookies containing a unique user ID to banner ads. Because these companies serve ads to thousands of different web sites, they can retrieve their cookies from all of these sites, too. Hence, although the site that carries the ad can't track your progress through the web, the company that serves the ads can. Sources:

How can I manage Cookies? ▪Use multiple browsers ▪Cookies are specific to each browser used: e.g. Firefox cannot read cookies from Google Chrome browser, nor any other browser. So you can use different browsers for different purposes. ▪However, some Web sites use them to track users as they browse the Web, collecting highly personal information and often surreptitiously transferring that information to other Web sites without permission or warning. ▪Disable cookies completely ▪This could have a major impact on your browsing experience (e.g. personal web site settings), and could even make some websites unusable. It may be appropriate to do this in one browser reserved for that purpose. ▪Control which cookies are accepted ▪There are tools to enable you to allow to, say: ▪accept only session cookies (not persistent ones), and/or only first-party cookies (not third-party ones); ▪accept cookies only from specified web sites; ▪delete persistent cookies (optionally only third-party ones and/or from specified sites) on closing the browser. Sources:

Browser Extensions - Terminology ▪Firefox refers generically to Add-ons, but splits them into Extensions & Plug-ins ▪Google Chrome refers to them all as Extensions ▪Opera refers to them all as Extensions in one place, and as Add-ons in another place! ▪Vivaldi refers separately to Extensions and Plug-ins ▪Safari refers to them all as Extensions ▪Microsoft Edge does not yet supports Extensions / Add-ons ▪So, I suggest treating: Add-ons = Extensions, optionally with Plug-ins as a sub-set

Browser Extensions – Browser engine ▪Browser extensions are specific to the browser engine, thus: ▪Extensions for Firefox cannot be used/installed in other browsers & vice versa ▪But extensions for the Google Chrome browser can be installed in other browsers built using the same browser engine ▪Many extensions are made available for (at least) the most popular browsers, but some extensions may be available only for selected browsers

Browser Extensions – Functionality ▪Some browser extensions provide additional – sometimes almost essential – functionality to the browser, which may be required for certain web pages to display properly; e.g. Adobe Flash ▪Some extensions allow you to tailor your browsing experience by controlling cookies, advertisements, etc.. ▪Other extensions provide auxiliary functionality to facilitate, for example: printing web pages; bookmarking web pages; retrieving frequently used web sites; extracting data, articles, etc. from web pages and storing them in an auxiliary application; storing & retrieving passwords & other registration / log-in data. ▪Yet other extensions provide additional buttons and/or toolbars to facilitate access to some features or functionality. ▪You can also use extensions (sometimes called ‘Themes’) to facilitate customisation of the overall appearance of the browser.

My customised Firefox screen Additional toolbars Buttons for managing cookies, etc. Buttons for frequently used functions and for managing tabs & window sessions Buttons for actions related to the web address Pinned tabs Pop-out side panel Buttons for printing & similar actions Buttons for bookmarking web sites Browsing history Downloads Extensions Web page info

Lists of Extensions and Plug-ins in my customised Firefox

Blocking web advertisements ▪Pros: ▪Adverts get in the way of reading web pages ▪Adverts can be distracting when viewing web pages ▪Adverts can slow down loading of the web page ▪Cons: ▪Adverts on web sites are little different from adverts in newspapers & magazines ▪Adverts can introduce you to useful products or services ▪Many free web sites rely on advertisements for funding ▪Without adverts, some web sites may not survive ▪Some ad-blockers claim to be ‘ethical’ and/or selective in what adverts they block For further information see: Are ad blockers good for the internet?Are ad blockers good for the internet?

Choice of ad-blockers ▪Beware that there are many ad-blockers with similar names but from different sources and with different functionality ▪Search for suitable ad-blockers within the ‘Add-ons’ or ‘Extensions’ menu / section of your browser. ▪I currently use Ad Blocker Ultimate, which gives me information as shown here (Note that Ad Blocker Ultimate was previously known as AdBlock Ultimate, but its name was changed following a complaint from AdBlock Plus)

▪Chrome ▪Internet Explorer ▪Firefox ▪Safari ▪Opera ▪Yandex ▪Edge browsers

Installing & using Extensions ▪You need to search for – and install – extensions while using the respective browser. ▪Some extensions (but not all) will require you to restart the browser in order to complete the installation. If you are installing several extensions at the same time you should be able initiate the installation of all of them and then do a single browser restart, rather than restarting the browser after each individual installation. ▪Many extensions will have options you can set to control their behaviour ▪Some extensions will automatically install buttons to access them, whereas others may provide buttons for installation and use of desired. Others may not need buttons. ▪All extensions should be available through an ‘extensions manager’ and all can be uninstalled if not required or if their behaviour conflicts with other extensions.