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Web browsers come in many flavors and varieties,

and if you're creating websites, it's important to be aware of what's out there.

Let's take a look.

There are many different browser layout engines

and perhaps even more browser vendors.

There are so many browsers out there, in fact,

that we're just going to focus on some of the major ones.

There are numerous reasons to be aware of all of the browsers available.

For one, it can greatly impact the end-user experience,

which is what this is all about.

However, the primary thing to be aware of

is cross-browser compatibility, which I talk all about

in the chapter on Browser Testing.

Often times, your website will look different when displayed in different browsers,

so let's go over some of the major options

that users have in the browser market today.

First up is Internet Explorer.

For most developers, IE can be painful to deal with,

especially older versions.

Historically, Microsoft has been slow to adopt draft specifications

and new browser technologies.

Additionally, older versions of Internet Explorer

have many bugs in their implementation

of W3C specifications.

So even if your CSS is valid,

you might still have issues making your page render

the way you'd like it to in Internet Explorer 6 and 7.

The current version, which is Internet Explorer 8,

has much better support for CSS2.1,

but it's adoption rate amongst users has been very slow.

As of this recording, all versions of Internet Explorer combined

sits somewhere between 60 and 50 percent market share,

depending on where you get your statistics from.

This is the majority share, so for any commercial website,

it's fairly important that it's tested to work properly in Internet Explorer.

Next up is Firefox.

The Firefox web browser is managed by the Mozilla Corporation,

and as of this recording, has roughly 22 percent marketshare.

To render web pages, Firefox uses the open-source Gecko layout engine,

which is also developed by the Mozilla Corporation.

The Gecko layout engine is pretty good,

and features much better standard support than the closed-source

proprietary engine used by Microsoft,

which is called Trident.

By using an open-source rendering engine,

anyone can review Mozilla's code

and submit bug fixes and changes for approval.

By having thousands and thousands of people looking at the code,

it tends to improve more rapidly.

Next is the Chrome web browser,

which is maintained by Google

Chrome is the newest of the major browsers,

only having emerged in late 2008,

but it's currently in third place with about 7 percent market share.

This may not sound like a lot of users,

but for having came out just two years ago,

the market share of Google Chrome is increasing

pretty rapidly every quarter.

Google Chrome has some of the best standards support

of any web browser available right now,

and it is based on the WebKit layout engine.

The WebKit layout engine is an open-source project

that is primarily maintained by Apple,

although many other companies contribute to its development.

The WebKit layout engine is used in many smaller, lesser-known web browsers,

and it is currently one of the dominant layout engines on mobile devices worldwide.

Speaking of Apple, next up is Safari.

The Safari web browser is maintained by Apple,

and it's closed-source with some open-source components.

One of the most important parts, the layout engine,

is open-source, because as you might have guessed,

Apple utilizes the WebKit layout engine.

Much like Google Chrome, Safari has some of the best standard support

currently available, and is sometimes even better than Chrome,

because they constantly are including the latest updates

to the WebKit rendering engine.

Safari has just under 5 percent market share,

but when combined with Chrome,

this amounts to a significant portion of web users

on the WebKit rendering engine.

The last browser we're going to look at is Opera,

which is in fifth place amongst the major desktop browsers.

Opera is developed by Opera software,

and also features excellent standard support.

At roughly 2 percent market share,

they don't have much of the desktop market,

but like WebKit, the Opera browser is featured prominently

on mobile devices worldwide.

With so many browsers, you might be wondering,

"How does one keep up?"

Well, one way to ensure that your website works

across all major browsers is to validate your code.

You can assume that browsers will, for the most part,

conform to the specifications outlined by the W3C.

Be aware, however, that there are many minor discrepancies

that might not always be easy to spot.

For this reason, it's important that you test all your code

directly in all the browsers you're planning to target.

Besides all the different layout engines available,

there's one more important concept to understand

that you'll most commonly encounter inside of web browsers,

and that's how url's work.

Url is an acronym for "uniform resource locator"

and it's the thing that you type into your address bar

that's typically located at the top of your web browser.

In a nutshell, when you type in a url,

it goes through a complex network of special computers called servers

and then the server you're looking for will send back HTML and CSS to your browser.

Your browser, or your computer, is known as a "client,"

and this relationship is called "the client/server relationship."

It's more complex than that, but that's all you need to know for now.

What's more important to understand right now

are the basics of parsing a url.

A url has many parts.

First, is the scheme, or protocol.

In this case, we're using the http protocol,

or "hypertext transfer protocol"

to transmit HTML, CSS, javascript, and other bits across the web.

There are many other schemes and protocols,

one of which we'll be going over in an upcoming video.

Next, is the domain name, such as google.com or w3c.org.

A registered domain name, or IP address,

gives the url a basic destination.

The second part of the domain name is the tld, or "top level domain."

This is the .com, .net, or .org portion of the domain name.

There are many others for different purposes,

and most countries have top-level domains as well.

As an example. .com means "commercial,"

and is intended for commercial use.

.org is for organizations, and so on.

Last is the path.

The path identifies a specific folder or location on the destination IP

and provides the user with the information located there.

There are several other important parts of urls that I haven't gone over here

such as subdomains, query strings, and more,

but those are the basics that you need to know for now.

That about wraps things up for web browsers.

I encourage you to download different web browsers

so that you can test directly and try them out for yourself.

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