what is different between id and classes

**sarnatech** · 02-14-2011 11:12 AM

Hello Friends,

We need ways to describe content in an HTML/XHTML document. The basic elements like <h1>, <p> and <ul> will often do the job, but our basic set of tags doesn't cover every possible type of page element or layout choice. For this we need ID's and Classes. For example <ul id="nav">, this will give us the chance to target this unordered list specifically, so that we may manipulate it uniquely to other unordered lists on our page. Or we might have a section on our page that has no relevant tag to signify it, for example a footer, where we might do something like this: <div id="footer">. Or perhaps we have boxes in our sidebar for keeping content over there separated in some way: <div class="sidebar-box">.
These ID's and Classes the "hooks" we need to build into markup to get our hands on them. CSS obviously needs these so that we may build selectors and do our styling, but other web languages like Javascript depend on them too. But what is the difference between them?

Thanks

**adronhill** · 02-16-2011 04:17 PM

- The definition of a class can be reused throughout the file and a ID can be used once.

- ID is a specific element and the class is a class project.

- ID and the class should be used this way even if it is an important use of them. It adds an additional layer of semantic code, which can be useful style.

**italianstalion** · 02-18-2011 04:52 PM

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