The real work of developing the files that will bring the web site to life begin after the initial design phase is complete.
As with the design stage of a web site project, there is more to this than initially meets the eyes.
One of the many surprises that new "web masters" are in for, is when they find out that the HTML "standards" don't really exist in the real world.
Not only do different browsers react differently (sometimes
far differently) to perfectly "legal" HTML coding, the number of differences in the way such things as Java script, style sheets, and other (more proprietary) extensions are handled is simply stunning!
To add insult to injury, many of the tools available for building web pages tend to output specific coding that is "optimized" for one particular browser or another.
This coding sometimes produces surprising (and often undesired) effects when the page is viewed with another browser.
Another area that requires its own level of expertise is image creation and manipulation.
The sheer number of available tools, file type specifications, manipulation techniques and quality/file-size trade-off factors can be astounding.
Suffice to say, this field is considered a career in and of itself!