Plugins are a small add-on that does a specific job. It is a collection of PHP files that has some functions.
Plugins are developed and released on the WordPress.org site and with the WordPress software, we can search and install those plugins on our site.
plugins are a small piece of a program that helps to perform a specific task.
Once you install the plugin you can update, uninstall, delete the plugin from the WordPress dashboard.
only admin can install or delete a plugin on your site.

Most famous plugins are used to:

• Increase Site Speed
• Site Analytics
• Stop the spam Comments
• Secure your site from Virus Attacks
• Add Contact Form to your site
• Reduce Media Size
• Backup your site

Some Important plugins

Classic Editor

Akismet Spam Protection

Jetpack – WP Security, Backup, Speed, & Growth

Classic Widgets

Rollback Update Failure

Contact Form 7

Yoast SEO

Elementor Website Builder

WooCommerce

Wordfence Security – Firewall & Malware Scan

Really Simple SSL