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Cloud Computing Explained
IaaS, PaaS, SaaS, and cloud service models
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Cloud computing means using remote computers on the internet to store data, run applications, and deliver services instead of relying only on a local device. It matters because it lets people and organizations access powerful computing resources from almost anywhere. A phone, laptop, or school computer can connect to cloud services for email, file storage, streaming, coding platforms, and collaboration tools. This makes computing more flexible, scalable, and often cheaper than buying and maintaining all hardware locally.
In a cloud system, a user device sends requests through the internet to data centers filled with servers, databases, and networking equipment. The cloud provider manages much of the hardware, security, updates, and resource allocation behind the scenes. Services are often grouped as infrastructure, platforms, or software, depending on how much control the user needs. Good cloud design balances performance, reliability, cost, privacy, and security.
Key Facts
- Cloud computing delivers storage, processing power, and software over the internet.
- Client device + internet + cloud data center = basic cloud computing path.
- Latency is the delay between a request and a response, often measured in milliseconds.
- Availability = uptime / total time, so 99.9% availability allows about 8.76 hours of downtime per year.
- Cloud scaling means adding or removing computing resources to match demand.
- Common service models are IaaS, PaaS, and SaaS.
Vocabulary
- Cloud computing
- Cloud computing is the delivery of computing services such as storage, servers, databases, and software over the internet.
- Data center
- A data center is a facility that contains many networked servers used to store, process, and deliver digital information.
- Scalability
- Scalability is the ability of a system to increase or decrease resources as demand changes.
- Virtualization
- Virtualization is the technique of creating software-based versions of computers, servers, or storage so one physical machine can act like many separate systems.
- SaaS
- Software as a Service is a cloud model where users access a complete application through the internet without managing the underlying hardware or software infrastructure.
Common Mistakes to Avoid
- Thinking the cloud is not physical, which is wrong because cloud services run on real servers inside real data centers.
- Assuming cloud storage is always private, which is wrong because privacy depends on permissions, encryption, account security, and provider policies.
- Confusing syncing with backup, which is wrong because syncing may copy deletions or mistakes across devices while a backup preserves recoverable versions.
- Ignoring latency, which is wrong because even powerful cloud servers can feel slow if network delay is high or the connection is unreliable.
Practice Questions
- 1 A cloud service has 99.9% availability over a 30-day month. How many minutes of downtime are allowed in that month?
- 2 A student uploads a 600 MB video to cloud storage using an upload speed of 20 megabits per second. About how many seconds will the upload take, assuming 1 byte = 8 bits and no overhead?
- 3 A school is choosing between running its own server room and using a cloud provider for a new learning app. Explain two reasons the cloud might help and one risk the school should manage.