Sometimes it is necessary to block access to the shop, especially when you want to change something or when you're working on template etc. In this case "Maintenance" mode is very helpful. This is basic feature in default prestashop installation - it mean that You don't have to install external modules because

Prestashop and maintenance communicate for customers

How to turn on maintenance mode?

Open preferences > maintenance tab in your back office. You will see maintenance configuration page. This page only has two options: Enable shop & Maintenance IP.

Enable Shop

You can enable or disable shop. To enable shop you have to select [yes] option. To turn maintenance on, you have to select [no]. Your website will not be visible anymore - also you will not have an access to front office. If you want to browse shop pages, you need to define own ip address in maintenance IP field

Maintenance IP

Maintenance IP field defines IP addresses for which shop will be visible even if it is disabled. This means that you can block access to the shop but still allow access to selected computers. It's great because you (or allowed persons) can browse store. You can define as many IP addresses as you want, just separate them by comma.

How to turn on maintenance mode - watch video