Please check below post. I hope that will help you
1) https://www.salesforce.com/products/

Sales Cloud
Grow sales faster with the world’s #1 CRM application.
1) http://www.salesforce.com/in/sales-cloud/overview/?d=70130000000lzaAAAQ

Service Cloud
Give your customers the support they deserve with faster, smarter service.
( From call-center software to self-service portals, our service solutions enhance your customer service with more responsive, more intuitive, more flexible support that anticipates customer needs.)
1) http://www.salesforce.com/in/service-cloud/overview/?d=70130000000lzaDAAQ

Marketing Cloud
Build and manage your 1-to-1 customer journeys with the world's most powerful digital marketing platform.
(Make the most of every customer interaction — creating personalised, cross-channel customer journeys that deliver exceptional brand experiences across email, mobile, social, Web, and more.)
1) http://www.salesforce.com/in/marketing-cloud/overview/?d=70130000000lzZ6AAI

Community Cloud
Empower customers, partners, and employees to tackle anything, anywhere with an online collaboration platform.
(Harness the power of social and mobile to create rich, engaging online communities. Build deeper customer relationships. Drive employee productivity and innovation. And empower resellers, partners, and distributors to get deals done faster.)
1) http://www.salesforce.com/in/communities/overview/?d=70130000000lzYpAAI

App Cloud
Welcome to the world’s #1 enterprise cloud platform, with all the tools and services you need to build apps.
( Today every company is in the app business. App Cloud is your one-stop shop for building, running, managing, and optimizing apps using the same technology and expertise that fuels our success. )
1) http://www.salesforce.com/in/platform/overview/?d=70130000000lza1AAA

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Public vs. Private Cloud Computing

Whether a public cloud or private cloud, everyone agrees that cloud computing key benefits include scalability, instant provisioning, virtualized resources and ability to expand the server base quickly.

The majority of public cloud deployments are generally used for web servers or development systems where security and compliance requirements of larger organizations and their customers is not an issue. Private cloud computing, on the other hand, by definition is a single-tenant environment where the hardware, storage and network are dedicated to a single client or company.

The public cloud is defined as a multi-tenant environment, where you buy a “server slice” in a cloud computing environment that is shared with a number of other clients or tenants.

Public Cloud Computing
Public clouds such as Amazon EC2 and Rackspace Cloud have a number of trade-offs:

• Utility Model – Public Clouds typically deliver a pay-as-you-go model, where you pay by the hour for the compute resources you use. This is an economical way to go if you’re spinning up & tearing down development servers on a regular basis.
• No Contracts – Along with the utility model, you’re only paying by the hour – if you want to shut down your server after only 2 hours of use, there is no contract requiring your ongoing use of the server.
• Shared Hardware – Because the public cloud is by definition a multi-tenant environment, your server shares the same hardware, storage and network devices as the other tenants in the cloud. Meeting compliance requirements, such as PCI or SOX, is not possible in the public cloud. 
• No Control of Hardware Performance – In the public cloud, you can’t select the hardware, cache or storage performance (SATA or SAS). Your virtual server is placed on whatever hardware and network, the public cloud provider designates for you.
• Self Managed – with the high volume, utility model, self managed systems are required for this business model to make sense. Advantage here for the technical buyers that like to setup and manage the details of their servers. Disadvantage for those that want a fully managed solution.

Private Cloud Computing
Private cloud hosting, on the other hand, by definition is a single-tenant environment where the hardware, storage and network are dedicated to a single client or company.
Private cloud computing also has a number of trade-offs:

• Security – Because private clouds are dedicated to a single organization, the hardware, data storage and network can be designed to assure high levels of security that cannot be accessed by other clients in the same data center.
• Compliance – Sarbanes Oxley, PCI and HIPAA compliance can not be delivered through a public cloud deployment. Because the hardware, storage and network configuration is dedicated to a single client, compliance is much easier to achieve.
• Customizable – Hardware performance, network performance and storage performance can be specified and customized in the private cloud.
• Hybrid Deployments – If a dedicated server is required to run a high speed database application, that hardware can be integrated into a private cloud, in effect, hybridizing the solution between virtual servers and dedicated servers. This can’t be achieved in a public cloud.

1) https://www.expedient.com/blog/private-vs-public-cloud-whats-difference/

hybrid cloud

Hybrid cloud is a cloud computing environment which uses a mix of on-premises, private cloud and third-party, public cloud services with orchestration between the two platforms. By allowing workloads to move between private and public clouds as computing needs and costs change, hybrid cloud gives businesses greater flexibility and more data deployment options.
http://searchcloudcomputing.techtarget.com/definition/hybrid-cloud

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