According WP Beginners, a plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites.
There are THOUSANDS of plugins available for free on WordPress.org and there are also loads of paid plugins for sale through third party companies that can help take your website to the next level.
Just like with anything you download, you must take care to ensure the plugin comes from a reputable source so that your website functions as you expect it to after it is downloaded and installed.
Here is a list of some of my must-have plugins – many of these I include on the sites I build when you work with Madison Reid Creative

Coming Soon Page, Under Construction & Maintenance Mode by SeedProd
Create a simple Coming Soon Page, Under Construction or Maintenance Mode Page. Work on your site in private while visitors see a “Coming Soon” or “Maintenance Mode” page.

Duplicate Posts, Pages and Custom Posts easily using single click. You can duplicate your pages, posts and custom post by just one click and it will save as your selected options (draft, private, public, pending).

Google Analytics Dashboard for WP (GADWP)
Enables you to track your site using the latest Google Analytics tracking code and allows you to view key Google Analytics stats in your WordPress install.

Supports your site’s security, performance, stats and analytics and SEO.

Build forms within minutes using our simple, yet powerful, drag-and-drop form creator. For beginners, quickly and easily design complex forms with absolutely no code.

Display Instagram posts from your Instagram accounts, either in the same single feed or in multiple different ones.

UpdraftPlus simplifies backups and restoration. Backup into the cloud directly to Dropbox, Google Drive, Amazon S3 (or compatible), UpdraftVault, Rackspace Cloud, FTP, DreamObjects, Openstack Swift, and email.

WooCommerce is a flexible, open-source eCommerce solution built on WordPress. Whether you’re launching a business, taking an existing brick and mortar store online, or designing sites for clients you can get started quickly and build exactly the store you want.

Helps your website rank higher in search engines.