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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.
There is a list of WordPress plugins, and links to other repositories, in Plugins.
WordPress Plugin Compatibility indexes plugins compatible with various WordPress versions.
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.
There are a few things you need to know before you begin to install WordPress Plugins.
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.
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.
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(); } ?>
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:
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.
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:
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.
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.
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.
If your theme relies on one or more plugins in order to correctly function, you may be interested in Jonathan Leighton's article explaining how to set up plugin dependencies.
Once you start using WordPress Plugins, you sometimes wonder how you ever got along without them. If you have knowledge of PHP, you can develop your own plugins, and there is a comprehensive list of resources at Plugin Resources to get you started.