The <perch:every></perch:every> tags are used within a template which outputs multiple items. They can be used if you need to output something different every other item, or every 3 items and so on.

<perch:every count="3">
    This happens every 3 items.

<perch:every nth-child="odd">
    Odd items only

<perch:every nth-child="2n+3">
    You can use nth-child values in the same way as in CSS selectors

Attributes for every

Attribute Value
count A simple integer. A value of 3 would match for every third item.
nth-child An alternative to count. Takes CSS-style nth-child values including keywords

Else blocks

Every also supports an else block. It is used if the ‘every’ condition is false.

<perch:every nth-child="odd">
    Odd items
<perch:else />
    Even items