Ajax is a group of interrelated web development methods used on the client-side to create asynchronous web applications. wikipedia.org

WordPress is a free and open source blogging tool and content management system (CMS) powered by PHP and MySQL. It has many features including a plug-in architecture and a template system. wikipedia.org

PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. wikipedia.org

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles. wikipedia.org

Node.js is a software system designed for writing highly-scalable internet applications, notably web servers. Programs are written in JavaScript, using event-driven, asynchronous I/O to minimize overhead and maximize scalability. wikipedia.org

React is an open-source JavaScript library for creating user interfaces that aims to address challenges encountered in developing single-page applications. wikipedia.org

Social media marketing refers to the process of gaining traffic or attention through social media sites. wikipedia.org

Xero is an online accounting software product for small and medium-sized businesses, as well as for personal finance. The product is sold by subscription (a distribution model commonly known as Software as a Service or SaaS) requiring the payment of a monthly fee. wikipedia.org

Customer relationship management (CRM) is a widely implemented strategy for managing a company's interactions with customers, clients and sales prospects. wikipedia.org

Pipedrive CRM is a highly popular sales management tool designed to help small businesses master the selling process. It works especially well for businesses where the sales cycle is long and many people are involved.

Zapier connects the web apps you use to move data and automate tedious tasks. wikipedia.org

A multisite network can be very similar to your own personal version of WordPress.com. End users of a Wordpress multisite network can create their own sites on demand, just like end users of WordPress.com can create blogs on demand.