What is Cloud Computing ?
Cloud computing is the delivery of computing services over the internet such as storage, servers, infrastructure, databases, networking, software, analytics and intelligence.
With cloud computing business can optimize cost, speed, security, productivity and performance.
So in simple words we can say that cloud computing is a modern day innovation in which the businesses uses the services provided by third party business over internet (like storage, server, infra and databases) so as to minimize the the overhead cost and time of maintenance and thus improving productivity and performance.
Before cloud computing came into picture companies used to build there own data center. Data center is place where all the servers are stored but in the cloud era companies does not require to create their own data center instead they can use subscription based model in which they can use the servers that is being maintained by some other third party.
Private and Public Cloud what is it ?
To understand private and public cloud we have to start from basics that is before the cloud.
Before cloud came into picture each organization used to buy a server and deploy a application on so that it can used by its customers but there was much wastage of resources for example we can say that we have application has requirement of 5 Gb of storage and 10 CPUs but the server has capacity of 100 Gb and 25 CPUs, since we deployed our application on it the remaining 95Gb and 15 CPUs are wasted and not used at all.
Therefore to overcome this problem of wastage of resources the concept of VIRTUALIZATION came into picture where we created multiple virtual server from an actual server and the IP address of these servers are shared with the developer whenever he request for the server of specific capacity.
This virtualization concept is called private cloud and due to advent of private cloud large companies like Amazon, google and Microsoft saw an opportunity and came with the concept of public cloud.
In public cloud the servers are created by one cloud provider like aws, gcp or azure and given to the public for use according to their need and subscription.
Why Public Cloud?
Public cloud became more popular because it reduced the maintenance overhead for the companies like they don't need to have a dedicated team to look after data centers and see that it is running fine or not, severs are not being hacked and also to patch if something goes wrong . in overall it reduces cost and increased productivity by increasing focus on business requirement rather than being focused on infrastructure management.