MySQL is a type of structure/query language-based open source relational database management system. It can be used in many applications, but most commonly it is used in combination with PHP to create dynamic websites, since most of PHP scripts require a database, which is almost always MySQL.

PHP is a widely-used open source scripting language that is specially designed for web development to produce dynamic web-pages.

Store Manager is the desktop application for Windows operation system. It is aimed at the simplification and acceleration of your store administration. This solution was specially developed to extend the functionality of your admin web interface by smart desktop advantages and make your general store management more convenient than from difficult-to-use store backend.
Store Manager accelerates all the parts of store management and makes it more efficient. Using it you can handle mass changes of your products, categories, orders and customers, take advantage of new features developed, leading single as well as multi-store management.

Store Manager Addon - the application built-in Store Manager and can be used only in combination with it. Addons extend the functionality of Store Manager itself or provide users ability to integrate with other sales channels or systems.

BackUp is the set of copied data from your database saved with the purpose of preserving data. It is the kind of insurance that your data will be save in case of any damage or loss.

Restore  is the process of recovery of your data from your previously saved backup after any loss or failure.

Update Service is the ability to download the latest versions of Store Manager which are regularly released.  After ordering the software, you can download new versions of this product during 6 months free of charge. After this period expires and you’d like to continue updating your Store Manager to the newest versions, you have to purchase update service for 6, 12 or 24 months.

Direct Connection - the way of connection to your remote database through which all the data changes will be directly reflected in your remote MySQL server database.
This type of connection allows you to see your live store database on your local PC and make changes instantly without any additional synchronization actions.
Using direct connection, your computer initiates outgoing connection directly to the host computer and host computer accepts incoming connection. This is a relatively simple way to make connection when host computer allows direct MySQL connection. However, if the host computer is behind a firewall you may not be able to access it from your home computer. In such cases you should add your IP to the White list (Access Hosts) using your store control panel in order to allow direct connections from specified IP address. Direct connections from IP addresses that are not whitelisted will be blocked.

PHP-MySQL Bridge is one of the ways to connect to your database. Using it you can work with your database locally, which means that the changes and all the data uploaded will be stored temporarily somewhere in local copy of your database created at your computer.
Bridge is used only for two major operations - retrieve data from remote database and post data (from your local database) to actual store database.
You must understand the difference between bridge connection and MySQL connection. Bridge is not a connection itself, actually this is just a way to transfer files between remote and local machine and nothing more.

HTTP Tunnel -  is an alternative way of connecting to your database and it possesses the features of both direct and bridge connection. This type of connection is useful if you don't have direct access to MySQL database, and you don't need to do POST \ GET operations each time to refresh data, since they are done automatically.