1. WordPress Plugins

2. What’s a Plugin?
Plugins are used to add functionality and features to your site. You can use plugins to make it easier to create content, create forms for feedback, etc.
Sometimes plugins become part of WordPress core – examples are Akismet and Hello Dolly.
There are currently over 25,000 plugins available to add functionality to WordPress sites.

3. Obtaining Plugins You can obtain plugins in a number of ways:
From within your Dashboard: Plugins > Add New
From 3rd party vendors

4. Installing a Plugin To install a plugin:
Log into your site as an admin.
In the Dashboard, go to Plugins>Add New.
If you’re searching for a plugin, search and locate it; if you have already downloaded a plugin, click Upload and then upload the plugin.
Click Install Now.
To activate, click Activate.

5. Some Plugins Allow PHP in Posts and Pages Column Shortcodes
Custom Content Type Manager
Custom Headers and Footers
Disable Comments
Display Posts Shortcode
Duplicate Post
Excerpt Length
Easy Contact Forms
FitVids for WordPress
Google Analytics for WordPress
Google XML Sitemaps
jQuery Image Carousel for WordPress
Lux Vimeo
Modernizr
Nice PayPal Button Lite
Post Duplicator
s2Member
Search Everything
Simple Local Avatars
Social Media Widget
Spider Event Calendar
Unique Headers
WordPress HTTPS
Wiziapp
WP Float
WP Include File
WP jQuery Text and Image Slider
WP Lightbox 2
WP Mobile Edition
WP Super Cache
WP User Avatar