The :odd selector selects every element with an odd index number (1, 3, 5, etc.). This is often used to create a striped row look in HTML tables.

// selects all odd numbered rows in an HTML table
$('tr:odd')

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To select multiple HTML elements with varying ids and classes, separate them with commas. The following will select 4 different elements based on their ID, class, or tag.

$('#intro, #footer, .my_paragraphs, h3')

To be more specific when selecting an HTML element, you can refer to the element and an ancestor element.

// all .child elements that live within a .father element
$('.father .child')

// all h1 tags that live within a .father element
$('.father h1')

Notice that there is no comma between the classes (but there is a space), which says you are targeting the class .child and it must have an ancestor with the class .father, as shown in the first example. You can include as many ancestors as necessary to be as specific as necessary.

// all p tags that live within a .child element that lives within a .father element
$('.father .child p')

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