Cloud computing lets organizations rent compute, storage, and networking capacity instead of owning physical servers. The main models are infrastructure as a service, platform as a service, and software as a service, each shifting a different amount of operational responsibility to the provider. Pricing is usually usage-based, which helps startups scale without large upfront capital spending. The trade-offs include vendor lock-in, data residency rules, and the need for careful cost monitoring when workloads grow unexpectedly.