Short answer. Make a change to any style of typeface or object on one place and effect all pages where it is used. Think of it as a 'Library' of 'definitions'. An example would be, if you had defined h1 as red and wanted to change it to blue, you make the change in the CSS and it changes all instances. Go to w3schools.com and get educated.
CSS is used for Code reusability Clean code Easy handling of styling from a single file and more Any text editior can be used for this
CSS can be used locally by the readers of web pages to define colors, fonts, layout, and other aspects of document presentation. It is designed primarily to enable the separation of document content (written in HTML or a similar markup language) from document presentation (written in CSS). This separation can improve content accessibility, provide more flexibility and control in the specification of presentation characteristics, and reduce complexity and repetition in the structural content. CSS can also allow the same markup page to be presented in different styles for different rendering methods, such as on-screen, in print, by voice (when read out by a speech-based browser or screen reader) and on Braille-based, tactile devices. CSS specifies a priority scheme to determine which style rules apply if more than one rule matches against a particular element. In this so-called cascade, priorities or weights are calculated and assigned to rules, so that the results are predictable.
If you decide to make a change in style to your website it can be altered instantly without the need for manually altering the font/style of each individual web page
I like CSSEdit for Mac, and TopStyle for PC. Sure, you can use notepad if you want to try and remember everything or you've got your reference book in your lap.
Don't forget it can also save BANDWIDTH, and can save handshakes too through the use of techniques like image reduction. Anything you can declare in the CSS that is shared on multiple pages of your website will save bandwidth and speed page-loads. Your general page layout is usually consistant across all pages on a site - as such anything you declare in your CSS is already cached after the user visits your first page, they go to another page on your site and all that appearance info is already on their machine. It also simplifies adding/removing content if you are working directly with flat HTML files, AND simplifies controlling your output from PHP/ASP/CGI/SSI of choice as you can concentrate on using one or two tags in your code, instead of having to have ten to twenty tags with hordes of attributes making it hard to tell your CGI/SSI code apart from the HTML it outputs. It is also LESS overall code, therin easier to maintain. For example old school flat html you might have a section of news items all coded thus: <TABLE BORDER="1" CELLPADDING="0" CELLSPACING="8" BGCOLOR="#CCCCCC"> <TR> <TH BGCOLOR="NAVY"> <FONT COLOR="WHITE">Jimbo makes a killing</FONT> </TH><TH BGCOLOR="NAVY"> <FONT COLOR="WHITE">10/27/2007</FONT> </TH> </TR><TR> <TD COLSPAN="2" BGCOLOR="#EEEEEE"> Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. </TD> </TR><TR> <TH BGCOLOR="NAVY"> <FONT COLOR="WHITE">Quando Omni Flunkus Moritati</FONT> </TH><TH BGCOLOR="NAVY"> <FONT COLOR="WHITE">10/27/2007</FONT> </TH> </TR><TR> <TD COLSPAN="2" BGCOLOR="#DDDDDD"> Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum </TD> </TR> </TABLE> Code (markup): Which comes in at almost 1k. 'modern' coders would use the following HTML (or something similar) to do the same thing: <div class="newsItem odd"> <h2>Jimbo makes a Killing <span>10/27/2007</span></h2> <p> Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. </p> </div> <div class="newsItem even"> <h2>Quando Omni Flunkus Moritati</h2> <p> Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum </p> </div> Code (markup): Which at 630 or so bytes is two-thirds the size and a HELL of a lot easier to see what's going on... The CSS for that: * { margin:0; padding:0; } .newsItem { color:#000; background:#CCC; padding:8px; } .newsItem h2 { margin-bottom:8px; padding-right:8em; font:bold 100%/120% serif; color:#FFF; background:#008; } .newsItem h2 span { display:block; margin-top:-1.2em; text-align:right; } .odd p { background:#EEE; } .even p { background:#DDD; } Code (markup): At 379 bytes might seem like we're just breaking even - but what if there were ten news items instead of just two? Each news item on it's own 'old school' without CSS ends up 477 bytes, while the 'new way' it's only 315 bytes - it can add up quickly since the CSS would not change. ... and one simple look at the differences in HTML should make it apparant why the new way is 'better' and generally considered 'simpler'.
CSS is web design friendly not SEO friendly. if you want to make specific change in each and every page and on selected portion you just need to change in CSS file and the same changes will apply to each and every page, this will save time and makes website very well designed. Website with out having any external css also may get good rank, it just the code.
Yes, that is true. But who cares. If it'll get people removing things like "BORDER="0"" out of their HTML, I'll be happy. And the ;ess HTML you give to search engines, the easier it is for them to find content
you may change easier with css file and i think dreamweaver ise useful for css dreamweaver complete code automatically