MongoDB is an open-source and free Database service. It is a NoSQL Database and it is different than other Databases like MSSQL and MySQL. There is no requirement of predefined schema and data structure as it will be changed. Data will be stored in JSON-like documents in MongoDB.

Following are the steps to install MongoDB 4 on Centos 7. We belive you are logged in with root or sudo user.

1. Add MongoDB repository to mongodb-org.repo inside the /etc/yum.repos.d/ directory using command : vi /etc/yum.repos.d/mongodb-org.repo
   
   
2. Enter below details in mongodb-org.repo
   
   

   [mongodb-org-4.0]
   name=MongoDB Repository
   baseurl=https://repo.mongodb.org/yum/redhat/$releasever/mongodb-org/4.0/x86_64/
   gpgcheck=1
   enabled=1
   gpgkey=https://www.mongodb.org/static/pgp/server-4.0.asc
   

3. Once repository is enabled, install MongoDB using yum command as below.
   
   

   # sudo yum install mongodb-org
   

         You will need to press y when MongoDB ask for the GPG Key during installation.

4. MongoDB will install the below packages as per screen capture.
   
   

     mongodb-org-mongos.x86_64 0:4.0.14-1.el6                                      
     mongodb-org-server.x86_64 0:4.0.14-1.el6                                      
     mongodb-org-shell.x86_64 0:4.0.14-1.el6                                       
     mongodb-org-tools.x86_64 0:4.0.14-1.el6 
   

4. Start MongoDB and enable it to start on boot.
   
   

   sudo systemctl start mongod
   
   sudo systemctl enable mongod

5. You can use mongo command to verify the installation MongoDB version.
   
   

   mongo