Chromium is a free open Web browser based on Webkit. Chrome is the Google branded version of Chromium being pushed down the throat of the Internet world by the virus like links on the Google search page.
Read about Chromium at www.chromium.org/Home. Install Chromium in Ubuntu by searching for
chromium in the Ubuntu Software centre. Your version of Linux might have something similar to the Ubuntu Software Centre. Follow the links at www.chromium.org for any other operating system.
You cannot miss Chrome. Just visit the Google home page to see the big advert for Chrome, the one millions of people accidentally clicked, the tens of millions of people clicked thinking that Google was providing unbiased help instead of misusing their power to promote a product of financial benefit to them.
Chromium is open source. Chrome is NOT open source. you do not know what Google adds to Chrome or what they will add in the future. Chrome is no safer than Internet Explorer.
Webkit is a set of code used to perform the real work inside a Web browser. Anyone can slap together a Web browser using Webkit. Because Webkit is new, it is missing a lot of things considered standard in the main competitors. Google Chrome is updated almost every week in an attempt to catch up with Firefox.
There are areas where Webkit is slightly ahead, specifically some CSS3 features but every major Web browser is ahead somewhere in CSS and behind in others. The big difference is the monthly, and sometimes weekly, updating of Firefox and Webkit to fix CSS interpretation errors and add new features. Microsoft tends to make fewer updates to IE and make big changes in each release.
From a practical point of view, you could spend a few hours changing your Web site to fix Chrome/Webkit errors then find, at the end of the change, Google issued an update to reverse the way they interpret that part of CSS and you have to change your whole site again.
Chrome is the fastest growing Web browser and has passed Firefox based on the number of installations. Accidental Chrome installations are currently the second most common type of support call. The most common type of support call is the one where the user says their Web browser stopped working, the support person works out the user installed Chrome because it was on the Google page, and the user does not know they are using a completely different browser.
Chrome passed Firefox usage in 2011 and Internet Explorer usage in 2012. One thing helping Chrome seem popular is their code to fetch pages ahead of time to make page reading appear faster. You visit a page with links to four other pages. While you are reading the current page, Chrome is reading the other four. Chrome usage may appear up to ten or more times more popular than it really is. The only way to get a valid comparison would be to switch off prefetch in every Chrome in the world.
By the way, if you use Chrome on a pay by download network, you are paying for the download of every one of those pages you may never visit. People accessing the Web on mobile devices are receiving bills 10, 100, or even 1000 times larger than what they expect because of all the Chrome and apps data transfers that are not requested by the user. beware!
Browser choice is passionate subject for some people. As an example some people tell you that everything done by Safari is right and perfect but everything done by every other browser is wrong. Those people ignore the facts that Safari is just a pretty face on the same Webkit used by a heap of other browsers.
Firefox and Chrome/Webkit do a lot of things slightly different. There is no right or wrong about them. Firefox is more often right in the sense of doing something useful in situations where Chrome/Webkit fails to do anything. When Firefox and Chrome both do things useful but different, Firefox is more likely to make the most useful choice for consistent Web development.
Not matter what result is the easiest to use, it is easy to make an argument that the opposite is better. Historically Firefox and opera produce the most consistent results. Internet Explorer is all over the place because it does different things based on what is called
quirks mode. Chrome was all over the place because they were making so many changes to catch up with everybody else.
Today in the CSS area Chrome/Webkit is ahead of Firefox and behind Opera. In every other area Chrome is behind. In many cases Chrome does something useful for some people but does not let you change anything to fit other people. As a result some people rave about Chrome while others rank it down the bottom of the heap because there is something they cannot switch off.
Firefox users can choose to install Firebug for Web development, or to install another collection of tools for their use, or to install nothing. Chrome has something built in and no choice about using it or using the alternatives. based on using Firefox+Firebug along side Chrome, Firebug does more for you and in an easier to understand way. Chrome does less, it really confusing in the way it presents some information but some people like not having choice.
Border measurements include the border, padding, margins, effects, and scroll bars. The HTML/CSS/Internet standards are too slack to specify the width of the scroll bars or to provide a way to control the width Everything else can be specified but the way they work together varies from browser to browser because again, the standards are slack and browser developers have to make up things as they go.
Firefox displays things as specified. If you apply special effects in some situations, Firefox recalculates the space required when the effect is applied. You have the responsibility of testing all the combinations that can occur.
Chrome allocates space for effects before they are used. You end up with space wasted if you are not using the effects. The difference makes Chrome easier for people who want to use lots of CSS effects without thinking about anything but makes life really hard when you are running out of screen space and need to get rid of some of that unused space.
Some people like not thinking. Some people prefer the option to control what happens.
Opera is the Web browser with one of the CSS architects on board. Opera is closest to interpreting CSS to the point where CSS can produce pixel perfect Web pages. Opera consistently failed to make money and had to introduce stupid money making schemes that killed the popularity of Opera. If people really wanted to read every Web page pixel perfect every time, everyone would have purchased the commercial version of Opera and Opera would be the number one Web browser.
Chrome reduces the Web browser to the lowest common approach for people who want to not think. Firefox lets you choose to think or not think. Opera is the Web browser everyone would use if they wanted wanted to read Web pages pixel perfect every time. Chrome will win because it is a virus invading from the Google search page and because nobody is interested in privacy or efficiency and few people care about their data download bills.