If you want to install Odoo 11 on Debian 9 then this tutorial will be very helpful, giving you guidelines, step by step. Another thing that we will do is installing the Nginx web server and also configure it as a reverse proxy. Odoo, or as we know it from before OpenERP, is a simple and intuitive suite of open-source enterprise management applications like Website Builder, CRM, Marketing, Human Resources, eCommerce, Manufacturing, Project, and 
Warehouse Management, Accounting, and so on. More than 3.7 million people use it, both in startup and large companies, making this type of software one of the most popular in the world. You can find Odoo in two editions, the free Community edition and Enterprise edition. We have chosen to install and use the Community edition of Odoo.