Title: hook – Make WordPress Plugins

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#  Tag Archives: hook

 [  ](https://profiles.wordpress.org/jsmoriss/) [JS Morisset](https://profiles.wordpress.org/jsmoriss/)
9:39 pm _on_ October 3, 2017     
Tags: action, doingitwrong, filter, hook, output

# 󠀁[Is your filter going to break the layout?](https://make.wordpress.org/plugins/2017/10/03/is-your-filter-going-to-break-the-layout/)󠁿

If you’re not clear about the difference between WordPress actions and filters, 
you may end up breaking the page layout of WordPress – maybe days, months, or even
years after you’ve written and implemented a new filterFilter Filters are one of
the two types of Hooks [https://codex.wordpress.org/Plugin_API/Hooks](https://codex.wordpress.org/Plugin_API/Hooks).
They provide a way for functions to modify data of other functions. They are the
counterpart to Actions. Unlike Actions, filters are meant to work in an isolated
manner, and should never have side effects such as affecting global variables and
output. hook.

The difference can be difficult for new developers to grasp – after all, hooking
an action or filter runs your code, either way, right? Well, yes, it does, but filters
can be executed several times, in different locations as the webpage is being built(
headerHeader The header of your site is typically the first thing people will experience.
The masthead or header art located across the top of your page is part of the look
and feel of your website. It can influence a visitor’s opinion about your content
and you/ your organization’s brand. It may also look different on different screen
sizes., body, footer, etc.), and even in the admin back-end. More importantly, filters**
do not** send anything to the webpage! Filter hooksHooks In WordPress theme and 
development, hooks are functions that can be applied to an action or a Filter in
WordPress. Actions are functions performed when a certain event occurs in WordPress.
Filters allow you to modify certain functions. Arguments used to hook both filters
and actions look the same. receive their data / text as an argument, and then “return”
the modified (or original) data / text at the end. They do not use “echo”, “print”,“
printf”, etc. – they should not send anything to the webpage. If you need to output
something directly to the webpage, use an action – that’s what they’re for.

 [Continue reading →](https://make.wordpress.org/plugins/2017/10/03/is-your-filter-going-to-break-the-layout/#more-1138)

[#action](https://make.wordpress.org/plugins/tag/action/), [#doingitwrong](https://make.wordpress.org/plugins/tag/doingitwrong/),
[#filter](https://make.wordpress.org/plugins/tag/filter/), [#hook](https://make.wordpress.org/plugins/tag/hook/),
[#output](https://make.wordpress.org/plugins/tag/output/)