WordPress Plugins are composed of php scripts that add additional functionality to your blog. They offer new additions to your blog that either enhance features that were already available or add otherwise unavailable 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.
Installing Plugins
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.
There are two ways to do that:
WordPress built-in installer - search, install and activate completely in the Add New menu.
Traditional manual installation - get and expand zip files, upload to your sever, and activate.
Manual Plugin Installation
To install a plugin that is not in the plugin browser, you should follow the given steps.
Remember: BACKUP - just in case.
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.
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 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.
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.
If the problem persists and you cannot seem to solve it, just check for similar plugins that do the same work. You will find plenty!
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.
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 activate 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.
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.
Things to Know Before You Install
There are a few things you need to know before you begin to install WordPress Plugins.
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.
Developing Your Own Plugins
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, but detailed instructions are beyond the scope of this book.
Most Popular Wordpress Plugins
All in One SEO Pack - http://wordpress.org/extend/plugins/all-in-one-seo-pack/
It automatically Optimizes your WordPress blog for Search Engines: page titles, meta tags, keywords, and descriptions. This plugin allows you to configure them for either your entire blog or on a post by post basis.
Google Analytics for WordPress - http://wordpress.org/extend/plugins/google-analytics-for-wordpress/
The Google Analytics for WordPress plugin allows you to track your blog easily. It adds the asynchronous tracking code for Google Analytics and automatically tracks and segments all outbound links from within posts, comment author links, links within comments, blogroll links and downloads. It'll add custom variables while tracking to show you page views per author, post type, category or publication year. It'll also allow you to track AdSense clicks, add extra search engines, and even ignore certain user levels.
Contact Form 7 - http://wordpress.org/extend/plugins/contact-form-7/
Contact Form 7 can manage multiple contact forms, plus you can customize the form and the mail contents flexibly with simple markup. The form supports Ajax-powered submitting, CAPTCHA, and Akismet spam filtering.
Akismet - http://wordpress.org/extend/plugins/akismet/
Akismet checks your comments against the Akismet web service to see if they look like spam or not and lets you review the spam it catches under your blog's "Comments" admin screen.
Google XML Sitemaps - http://wordpress.org/extend/plugins/google-sitemap-generator/
This plugin generates a special XML sitemap which will help search engines like Google, Bing, Yahoo and Ask.com to better index your blog. With such a sitemap, it's much easier for the crawlers to see the complete structure of your site and retrieve it more efficiently. The plugin supports all kinds of WordPress generated pages as well as custom URLs. Additionally it notifies all major search engines every time you create a post about the new content.
WPtouch iPhone Theme- http://wordpress.org/extend/plugins/wptouch/
WPtouch automatically transforms your WordPress blog into an iPhone application-style theme, complete with ajax loading articles and effects, when viewed from an iPhone, iPod touch, Android, Opera Mini, Palm Pre and BlackBerry Storm mobile devices. The admin panel allows you to customize many aspects of its appearance, and deliver a fast, user-friendly and stylish version of your site to iPhone, iPod touch, Android, Palm Pre and BlackBerry Storm visitors, without modifying a single bit of code (or affecting) your regular desktop theme. The theme also includes the ability for your visitors to easily switch between the WPtouch view and your site's regular theme.
Fast and Secure Contact Form - http://wordpress.org/extend/plugins/si-contact-form/
This contact form lets your visitors send you a quick E-mail message. It also blocks all common spammer tactics. Spam will no longer be a problem because of its CAPTCHA and Akismet support. Additionally, the plugin has a multi-form feature, optional extra fields, and an option to redirect visitors to any URL after the message is sent.
NextGEN Gallery - http://wordpress.org/extend/plugins/nextgen-gallery/
NextGEN Gallery is a full integrated Image Gallery plugin for WordPress with a Flash slideshow option.
Post videos and photo galleries - http://wordpress.org/extend/plugins/post-rich-videos-and-photos-galleries/
This plugin lets you post your videos and photo galleries/flash slideshows easily and in seconds. It creates an automated, fully customizable image gallery, slideshows, video and music playlists anywhere within your WordPress site. You can then choose your videos, images and music and display skin, pages or posts with custom overlay text and a rotating thumbnail belts.
WP Super Cache - http://wordpress.org/extend/plugins/wp-super-cache/
This plugin for WordPress produces static html files from your dynamic WordPress blog. After a html file is generated your webserver will serve that file instead of processing the comparatively heavier and more expensive WordPress PHP scripts. The static html files will be served to the vast majority of your users, but because a user's details are displayed in the comment form after they leave a comment those requests are handled by PHP. Static files are served to:
Users who are not logged in.
Users who have not left a comment on your blog.
Or users who have not viewed a password protected post.
99% of your visitors will be served static html files. Those users who don't see the static files will still benefit because they will see regular WP-Cache cached files and your server won't be as busy as before. This plugin will help your server cope with a front page appearance on digg.com or other social networking site.
If for some reason "supercaching" doesn't work on your server then don't worry. Caching will still be performed, but every request will require loading the PHP engine. In normal circumstances this isn't bad at all. Visitors to your site will notice no slowdown or difference. Supercache really comes into it's own if your server is underpowered, or you're experiencing heavy traffic. Super Cached html files will be served more quickly than PHP generated cached files but in every day use, the difference isn't noticeable.
ourSTATS Widget - http://wordpress.org/extend/plugins/ourstatsde-widget/
This plugin create a widget for the ourstats.de counter service, which is a free Service to find out information about your visitors such as Screen resolution, browser, language and origin, page views by hour survey, as well as what keywords your visitors use to go to your homepage.
Yet Another Related Posts Plugin - http://wordpress.org/extend/plugins/yet-another-related-posts-plugin/
Yet Another Related Posts Plugin (YARPP) gives you a list of posts and/or pages related to the current entry, introducing the reader to other relevant content on your site. It has a very advanced and versatile algorithm which considers post titles, content, tags, and categories, and then calculates a "match score" for each pair of posts on your blog. You choose the threshold limit for relevance and you get more related posts if there are more related posts and less if there are less.
WordPress.com Stats - http://wordpress.org/extend/plugins/stats/
There are hundreds of plugins and services which can provide statistics about your visitors. However I found that even though something like Google Analytics provides an incredible depth of information, it can be overwhelming and doesn't really highlight what's most interesting to me as a writer. But this particular plugin just focuses on the most popular metrics a blogger wants to track and provide them in a clear and concise interface. Once it's running it'll begin collecting information about your pageviews, which posts and pages are the most popular, where your traffic is coming from, and what people click on when they leave. It'll also add a link to your dashboard which allows you to see all your stats on a single page. Finally, because all of the processing and collection runs on its own servers and not yours, it doesn't cause any additional load on your hosting account. In fact, it's one of the fastest stats system, hosted or not hosted, that you can use.
WP-PageNavi - http://wordpress.org/extend/plugins/wp-pagenavi/
This plugin adds a more advanced paging navigation to your WordPress site like :
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