Akismet – Helps block SPAM comments which are prevalent on WordPress sites. You need to generate a key to use the software, which is free on the Akismet website. You can also shut off comments completely to avoid having to deal with SPAM comments.
Better WordPress Google XML Sitemaps – This program will generate and cache a sitemap you can submit to Google through Webmaster Tools. Submitting a sitemap will help make sure that all the pages of your site are indexed by Google. It can also create a gzip version of your sitemap to save space and bandwidth.
Better WordPress Minify – Allows you to combine and minify your CSS and JS files to improve page load time. This plugin uses the PHP library Minify and relies on WordPress’s enqueueing system rather than the output buffer, which respects the order of CSS and JS files as well as their dependencies.
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, Akismet spam filtering and so on.
UpdraftPlus – Backup/Restore – Really powerful backup software that can upload complete backups directly to Dropbox, Google Drive, or other cloud providers. It can keep a fixed amount of backup copies, and automatically backup your site at an interval, daily, weekly, monthly, etc.
WordPress SEO by Yoast– Allows you to customize the title and description for each page or post. It shows you exactly how the page will look in a Google search.
WP-Optimize – A database cleanup and optimization tool. It doesn’t require PhpMyAdmin to clean and optimize your database tables, and can be set to automatically optimize the tables daily, weekly, etc.
WP Super Cache – Generates static html files from your dynamic WordPress site. After a html file is generated your webserver will serve that file instead of processing the WordPress PHP scripts
bbPress – Forum software. focused on ease of integration, ease of use, web standards, and speed.
BuddyPress – Social networking in a box. Build a social network for your company, school, sports team, or niche community.
WooCommerce – Excellent E-commerce software. Packed full of features, integrates into your self-hosted WordPress website.
What are plugins you think are most important for WordPress sites? Leave a comment below!