Overview
Attributes are name-and-value pairs used to define the characteristics of an HTML element, and are placed inside the element’s opening tag. There are many different attributes depending on the HTML tag being used. But the main three are the id, class, and style attributes.
The name is the property you want to set, and the value is the value of the property and is always put inside quotations.
ID Attribute
The following provides an id to a paragraph of text and one to an image. An id is like a nickname – a very important nickname. We may use it to refer back to the element using CSS or JavaScript and since it’s a very important nickname it will take precedence over other minor nicknames (the class attribute).
<p id="main_paragraph">This is a paragraph.</p>
<img decoding="async" src="/images/logo.png" id="logo_image" alt="My Logo" />Note
Elements on a page must not share and id. Each element has to have a unique id. However, an element’s id can be the same as an element’s id on a different page.
Note
It doesn’t matter in what order or where you place the attribute, so long as it’s inside the opening tag. For tags like the <img> tag that are self closing and have no actual closing tag, you can place the attribute anywhere before the closing />.
Class Attribute
The following uses the class attribute to provide a minor nickname to an element. It can also be used to refer back to the element using CSS or JavaScript, but if another rule in our CSS or JavaScript conflicts and is referring to the element’s id, the class (minor nickname) will be overruled by the id.
<p class="paragraph">This is a paragraph.</p>
<img decoding="async" src="/images/logo.png" class="image" alt="My Logo" />Note
Unlike an id, a class can appear in multiple elements on the same page. We could have 8 different paragraphs on the same page with the class “bolded_text”, but none can share an id.
Note
An element can have many class attributes separated by a space, but can only have one id attribute. In fact, an element can have a class that is the same name as its id.
<p id="main_paragraph" class="paragraph">This is a paragraph.</p>
<img decoding="async" src="/images/logo.png" id="logo_image" class="logo_image image no_border" alt="My Logo" />Style Attribute
The style attribute allows you to specify style rules within the element itself instead of placing them in a linked stylesheet. However, this should be done sparingly, as it’s not good practice. It’s better to keep all, or nearly all, of your styles in one place – the linked style sheet for your site or document.
The style attribute is followed by one or more CSS styles with the property coming first, then a colon, then the value of the property, and closed with a semi-colon (style=”color: red;”).
<p class="paragraph" style="color: red; font-size: 18px;">This is a paragraph.</p>
<img decoding="async" src="/images/logo.png" style="border-color: red;" class="image" alt="My Logo" />Note
Using the style attribute is called an “inline style” and will override any styling set in the linked stylesheet, even those referring to an element’s id (unless the stylesheet rule uses !important as part of its value).
HTML Notes:
- In our HTML section the term “tag” and “element” are often used interchangeably to refer to both the tag used to create a page element and the element created by the tag (<p> tag = <p> element = paragraph on the page)
- HTML5 is not case sensitive; so <P> is the same as <p>, <H1> is the same as <h1>
- Global attributes can be used with all HTML tags and are therefore not mentioned on every tag page
- To write clean, readable HTML code, it is best to use indentation whereas elements within elements are indented (tabbed or spaces) to create something that looks like a project outline
- The browser will automatically remove any extra spaces and lines in your HTML code when the page is displayed
- Double quotes or single quotes can be used around HTML attribute values, but when the attribute value itself contains one form of quote, it will be necessary to use the other around the attribute
We’d like to acknowledge that we learned a great deal of our coding from W3Schools and TutorialsPoint, borrowing heavily from their teaching process and excellent code examples. We highly recommend both sites to deepen your experience, and further your coding journey. We’re just hitting the basics here at 1SMARTchicken.