Software-as-a-Service (SaaS) provides on-demand software applications and executes them online instead of buying and installing them on a local computer. This software is installed on the host machine, and the cloud provider maintains the application on behalf of the company. It helps the company reduce the installation and maintenance cost related to IT infrastructure. Software-as-a-Service (SaaS) is also called as On-Demand Software.

Some of the SaaS applications are :

• Billing and invoicing system
• Customer Relationship Management (CRM) applications
• Mail Services
• Help desk applications
• Social Networks
• Human Resource (HR) solutions
• Document Management

SaaS applications may not be customizable, so it provides us Application Programming Interface (API), which helps the developer to develop a customized application.

The SaaS applications are cost-effective, the service provider does maintenance, and it can be easily scaled up and down as per the business requirement. Software-as-a-Service offers a shared data model, and all customers run the same version of the software. SaaS is globally accessible, and users can run software from any platform or device they want.

Some of the SaaS providers are NetSuite, Oracle CRM, Saleforce.com, Google Apps, Microsoft Office 365, Workday Inc, etc. 

Benefits of Software-as-a-Service (SaaS)

1. Cost Effective: SaaS offers monthly or annual subscriptions, so it is easy to buy for an organization because its cost is less as compared to licensed applications.
2. One to Many:  SaaS is based on a shared data model, so a single instance of the application is accessible by multiple customers at the same time.
3. Accessibility and Multidevice support: SaaS applications can be accessed globally from a remote location also, and these applications are device independent; we can easily access them by mobile, laptop, tablet, desktop, etc.
4. No Client-Side Installation:  The SaaS services are accessible directly via an internet connection, so the organization doesn’t require any in-house software or hardware installation.
5. Platform responsibilities managed by service providers: All the backups, storage, power management, security, maintenance, and installation are managed by the service provider, and users don’t have to bother about it.

Disadvantages of Software-as-a-Service (SaaS)

1. Network Dependent: All the services are accessible only via good internet connectivity, so there should be good internet connectivity for accessing the application on both sides.
2. Security: Since all applications are present in a cloud environment and security feature is managed by the cloud provider, and security is a major reason. In-house deployment is more secure than the cloud environment if anyone wants to work on confidential data.
3. Latency Issue: The data and applications are stored at a variable distance, so there may be greater latency while interacting with applications. This type of SaaS model is not recommended if we require response time in milliseconds. 
4. Vendor lock-in: Once the customer takes services from one service provider, they cannot switch to another vendor. It is time-consuming and expensive for the client working on a large application.