Cloud storage refers to a virtual storage area that can be extended across different storage devices, where a person or a organisation can store or access the data.
Examples for cloud storage are Dropbox, Google Drive, Mail services, etc.

Advantages:

1. Can share files with ease
2. Backup and recovery
3. Remote Access
4. Usability and accessibility
5. Cost Efficent

Prerequriment: 

1)Fresh Installtion of Ubuntu 20.04 with ssh enabled
2)Php 
3)Mysql/Maraiadb 
4)Apache2 

What is ownCloud?

ownCloud was established by Markus Rex, Holger Dyroff and Frank Karlitschek. ownCloud is a opensource, file server that empowers secure storage, joint effort and sharing. It is helpful to store records/data in the cloud, so they are accessible on any gadget/devices and can be imparted to a couple of snaps. ownCloud records are put away in regular registry structures and can be accessed through WebDAV if vital. There are a great deal of well known suppliers like Google, Apple, Facebook, Twitter and Dropbox.

Installation Step for ownCloud

Step 1: Update and Upgrade the repositories 

            sudo apt update && sudo apt upgrade -y 

Step 2: Enable Root Login 

sudo sed -i 's/#PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config 
sudo systemctl restart ssh 
sudo passwd 

Step 3: Install LAMP Stack in order to setup owncloud 

sudo apt install -y apache2 libapache2-mod-php mariadb-server openssl php-imagick php-common php-curl php-gd php-imap php-intl php-json php-mbstring php-mysql php-ssh2 php-xml php-zip php-apcu php-redis redis-server wget 

Step 4: Enable and start Mariadb and Apache services 

            sudo systemctl enable apache2 mariadb 
            sudo systemctl start apache2 mariadb 

Step 5: Secure the maraia db installation and enter "y" for every prompt 

            sudo mysql_secure_installation 

Step 6: Create database for owncloud 

create database owncloud; 
create user 'cloud_user'@'localhost' IDENTIFIED BY 'owncloud'; ////change password 'owncloud' as per your requirement 
GRANT ALL PRIVILEGES ON owncloud.* TO 'cloud_user'@'localhost'; 
FLUSH PRIVILEGES; 
exit; 

Step 7: Download the latest version of owncloud apllication from the offical-website: https://download.owncloud.org/community/ 

            cd /var/www/html
            sudo wget https://download.owncloud.org/community/owncloud-10.9.1.tar.bz2
            bzip2 -dk owncloud-10.9.1.tar.bz2  or  tar -xjf owncloud-10.9.1.tar.bz2
            sudo chown -R www-data. owncloud
Step 8: Enable a2enmod rewrite,header and restart apache2,httpd
            sudo a2enmod rewrite
            sudo a2enmod headers
            sudo systemctl apache2 restart  or sudo service apache2 restart
            sudo systemctl httpd restart   or  sudo service httpd restart

Now the installation of owncloud is completed. Open the browser and the ip-address/cloud

            http://ip-address/owncloud

Reference/Credit: https://doc.owncloud.com/server/10.9/admin_manual/installation/quick_guides/ubuntu_20_04.html
 
https://www.tecmint.com/install-owncloud-to-create-personal-storage-in-linux/