Plugins are cool bits of programming scripts that add additional functionality to your blog. They offer new addition to your blog which either enhance already available features or add new features to your site.
Plugins extend the functionality of WordPress. The majority of WordPress users don't require Plugins, or only require a few, such as Plugins dealing with comment spam or customized post listings. Other users enjoy the varied options Plugins provide such as frequently updated weather reports, post word counts, rating systems, and more. Since the choice in Plugins is vast, and chosen based upon the needs of the user, they are not incorporated into the core of WordPress.
WordPress Plugins are designed by volunteers and are free to the public. Plugins listed in the sources below have usually been thoroughly tested and considered "safe". But remember, Plugins are the responsibility of the author and the user, and they are typically works-in-progress as WordPress grows and expands.
If you want to develop your own plugins, there is a comprehensive list of resources at Plugin Resources.
Finding Plugins
There is a list of WordPress plugins, and links to other repositories, in Plugins.
Plugin Compatibility
WordPress Plugin Compatibility indexes plugins compatible with various WordPress versions.
Installing Plugins
WordPress Plugins Panel
WordPress Plugins Panel
WordPress offers simple and easy ways of adding Plugins to your blog. From the Administration Panels, click on the Plugin tab. Once you have uploaded a plugin to your WordPress plugin directory, activate it from the Plugins Management page, and sit back and watch your plugin work.
Not all Plugins are so easily installed, but WordPress plugin authors and developers make the process as easy as possible. We've included more detailed information on how to install Plugins below, as well as some things you need to know before you install.
Things to Know Before You Install
There are a few things you need to know before you begin to install WordPress Plugins.
Know before you install.
Read through the readme.txt files and web pages, as well as any comments regarding the Plugin on an author's website, before you install. The more you know before you install, the easier the process should be.
Plugins require downloading and uploading to install.
You must be familiar with how to download and upload files and how to use FTP, if required.
Plugins may require modifying WordPress files and templates.
Familiarity with PHP, HTML, CSS, and CHMOD may be necessary.
Record modifications.
If you make any changes to the WordPress files or templates, make a note of it in the code by using comments before and after the changes, and in a text file saved to your site and on your desktop to remind you of any additions or modifications to your default files or templates. This will help you repeat these in the future if there are any problems with your site.
Make frequent backups!
Some Plugins work independently of your blog's content and files, just adding a little something special to the page. Others require modification of content and files, including changes to your database. Before installing any plugin that will make dramatic changes, backup your database and files.
There are several versions of WordPress currently available, and different Plugins available for the different versions. Be sure and read through the information thoroughly to determine if the Plugin will work with your version, or check Plugins/Plugin_Compatibility. If not, consider upgrading.
Plugin Installation
To install a plugin, the following are the general directions to follow. Be sure and follow the specific instructions provided by the Plugin author. Remember: BACKUP - just in case.
Read through the "readme" file thoroughly that usually accompanies a plugin, or the website article from where you found the plugin. It is often helpful to print out the instructions so you can check off the installation steps as you complete them.
Upload the plugin to the wp-content/plugins folder in your WordPress directory online.
Make any changes to templates or files as required by the Plugin instructions including adding Plugin template tags.
Activate the Plugin:
Access the Plugin Panel in your Administration Panels
Scroll down through the list of Plugins to find the newly installed Plugin (if not visible, start from the beginning to check to see if you followed the instructions properly and uploaded the file correctly).
Click on the Activate link to turn the Plugin on.
Continue making any modifications necessary from the "readme" file instructions to make the plugin's actions meet your needs.
Hiding Plugins When Deactivated
Some plugins feature tags inside of the template files. If the plugin is not activated, it will "break" the Theme and it may report errors or fail to load. It is therefore imperative to prevent the plugin from being detected in case it is turned off.
To detect if a plugin is installed, you can use a simple function_exists() check. The if (function_exists()) checks for the plugin, and if it exists, it will use it. If it returns FALSE or "not found", it will ignore the plugin tag and continue loading the page.
<?php
if (function_exists('FUNCTION NAME')) {
FUNCTION_NAME();
}
?>
This example plugin uses a function called jal_get_shoutbox() to print out its contents.
<?php
if (function_exists('jal_get_shoutbox')) {
jal_get_shoutbox();
}
?>
Troubleshooting Plugins
If you are experiencing problems with a plugin you installed or one that stopped working after upgrading, the following are the steps you need to take to troubleshoot the plugin:
Check that you have followed the plugin author's instructions to the letter.
Check that any plugin tags or usage within your template files are correct, spelled right, and placed in the appropriate place, i.e., within the WordPress Loop or outside of it.
Check that you uploaded the file to the plugins folder under wp-content. If you are uploading a new version to replace the old, delete the old version prior to uploading the new one.
Check that the plugin has been activated in your Plugin Panel of your Administration Panels.
Deactivate and re-activate the plugin to see if this makes it work.
Visit the plugin author's website, typically linked from the Plugin Panel, and look to see if someone else is having the same trouble and an answer has been posted, or a new version released.
Contact the plugin author directly via their website or email requesting assistance.
Search the Internet for the name of the plugin and the trouble you are having as someone else might have had the same problem and found a fix and posted it on their site. TIP: Sometimes it helps to search for the plugin's filename.
Visit the WordPress Support Forum (or WordPressMU Support Forum for WordPress Multi-User installs) and post a clear question about the plugin and the problem you are having and you may get an answer from someone familiar with the plugin.
If the problem persists and you cannot seem to solve it, check to see if there are any similar plugins that you can try instead.
Upgrading WordPress May Break Plugins
Some plugins may become outdated and no longer work with the newer version of WordPress. If you have issues after activating a plugin, deactivate it and visit the Plugin's website to see if a newer version is available.
Many plugin authors will upgrade their plugins to accommodate the newer version, but some either won't, or their plugin becomes obsolete with the improvements in WordPress.
Plugin Management
Plugins are managed from the Plugins Panel in the Administration Panels of your WordPress site. All plugins listed on this screen are found in your wp-content/plugins directory. Each plugin has a description of what it does, an author and website to refer to, and a version number. If you do not see the plugin on the list, it is because it is missing the "header":
<?php
/*
Plugin Name: Magic Plugin
Plugin URI: http://example.com/magic-plugin
Description: Magic Plugin performs magic
Version: 2.3
Author: Mr. Magic
Author URI: http://example.com/
*/
You can add this information yourself by opening the plugin in a text editor and adding the above "comment", changing the information as follows:
Plugin
Shows the plugin's name, and links to the plugin's website if one is provided. Plugins listed in bold are currently active.
Version
The version number of the plugin.
Description
The author's description of what the plugin does and who authored the Plugin.
Action
Allows you to activate, deactive, or edit the plugin.
New version available
If a newer version of a Plugin is available in the WordPress Plugin repository a message will display along with a link to the location to download that new version.
Activation and Deactivation
If your plugin requires changes to the WordPress code or your template files, you will need to enact or reverse those changes each time you activate or deactivate your plugin. Failing to do this will likely result in errors. There is also a link provided below the list of Plugins that allows you to Deactivate All Plugins.
Uninstalling Plugins
While Plugins are very useful, some Plugins just don't meet your needs, or you've stopped using them for some reason, or they just don't work. After deactivating the Plugin stops the Plugin's behavior, they tend to pile up in your Plugins panel, making your plugin list long and cumbersome to scroll through. If left there long enough, they might become obsolete with the new WordPress versions and cause problems if you decide to use them in the future.
Plugin Admin Screen
Plugin Admin Screen
Begin your Plugins housekeeping by visiting the plugin author's site to see if there are instructions on how to uninstall the plugin via the Plugins panel on the left side of the screen. Some plugins require adding tags and code to your Template files while others require modification of the WordPress administration files. Be sure and read through the plugin's uninstall instructions to remove each of these modifications so your site will not have errors when the plugin is turned off.
If no specific instructions for uninstalling exist, then read through the installation instructions to check for modifications, if applicable, and reverse their changes, if implemented. If it has been a long time since you used this plugin, you still might have left its modifications in your template files and forgotten them. Carefully remove them.
To remove a plugin, make sure the plugin is deactivated from the Plugins panel. Go to your website's wp-content/plugins folder (usually with an FTP program) and look for the file name of the plugin you want to remove. Select the file name and delete it.
If have your WordPress site on your hard drive, open the wp-content/plugins folder on your site and find the file name of the plugin you want to delete, select it and delete it. This way, if you have to restore or copy your Plugin folder to your website, you won't restore the unwanted plugin on your site.
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