Why use Master table in project

Master table is use to store the basic information.which cannot need to change.

Pretty simple, reusability of data. Can be changed on need but some data no need of change, let's take real time scenario of project 'Marketing'. In this project there will be form to enter customer profile, another form enter sales order details so when customer orders you need to select customer from customer profile master table at sales order form to avoid typing customer details again and again unless he is permanent or long term customer. If customer shift his company to other area then you need change customer address which helps to you while transport his order to his address. Let's take another scenario HR project, here employee profile data is master table. Here employee blood group will not change so no need to change again and again