Cloud computing is defined as the sharing of resources rather than approaching applications by local servers. It is on demand due to advantages of high performance, low cost of services, scalability and availability.

Cloud computing deployment models express category of cloud environment and differentiate each other by size, occupancy and access.

According to NIST(National Institute of Standards and Technology), there are four deployment models:-

• Public Clouds
• Community Clouds
• Private Clouds
• Hybrid Clouds

1. PUBLIC CLOUDS- In this deployment model, services are transferred to various clients. Tis service may be free of cost or on the basis of license.

Best example of public cloud is Google, Amazon web services etc.

It is easiest model to access or purchase. This model is best for business because there it is utilize by many users.

Advantages-

•  Reliable
•  Flexibility
•  Location Independence
•  Cost effective

Disadvantage-

• Weak on security
• Customization is not possible
• Lacks proper control

2. COMMUNITY CLOUDS- In this model hosting is shared in a particular community which is used by many organizations. In this more than one group having common needs share this.

e.g of this is bank.

It can be hosted internally or externally.

Advantages-

• Lower cost
• Ability to collaborate
• Achieve goal easily

Disadvantages-

• Slow approval to date
• Not the right choice for every organization

3. PRIVATE CLOUDS- This model is also known as internal cloud. Private cloud allows only authorized users for access and having control over their data.

Advantages-

• Improve security
• Greater control over the server
• flexibility
• Superior performance
• Easy customization

Disadvantage-

• Difficult to access the data
• Capacity ceiling
• Cost

4. HYBRID CLOUD-  A Hybrid cloud is the combination of public, private and community which remains as individual entity. In this resources are managed by external providers or in home.

Advantages-

• Faster processing time
• On premise infrastructure
• Reduce and manage the code
• Highest level of security

Disadvantage-

• Communication in the network level may combat
• Security may break, if not used properly