SaaS stands for "Software as a Service". It is a model for delivering software applications over the internet, as a subscription-based service rather than as a traditional, locally installed software application.

In a SaaS model, the software application is hosted and maintained by the service provider, who makes it available to customers over the internet. Customers typically access the software through a web browser or mobile app, and pay a monthly or annual subscription fee to use the service.

SaaS has become increasingly popular in recent years, as it offers a number of benefits over traditional software models. These benefits include:

1. Accessibility: SaaS applications can be accessed from anywhere with an internet connection, making them ideal for remote work or mobile use.
   
   
2. Scalability: SaaS applications can be easily scaled up or down to meet changing business needs, without the need for expensive infrastructure investments.
   
   
3. Cost-effectiveness: SaaS applications are typically more cost-effective than traditional software models, as customers only pay for the features and functionality they need, and do not have to invest in expensive software licenses or hardware.
   
   
4. Maintenance and updates: SaaS providers are responsible for maintaining and updating the software application, freeing up customers to focus on their core business activities.
   

SaaS has become a popular model for a wide range of software applications, from customer relationship management (CRM) and human resources (HR) software to project management and accounting tools.