Hosting
Hosting is the service that stores your application's files (code, database, media files) and ensures they are accessible 24/7 over the internet.
In essence, you rent resources like CPU, RAM, ROM on a server, deploy your application there, and run it. This way, your application becomes accessible to everyone on the internet.
OSI Model (Open Systems Interconnection)
The OSI model is a standardized model that explains how computer networks operate, from physical hardware to software.
When data is sent from one computer to another, this process is carried out in the same order across all devices.
The OSI model consists of 7 layers:
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Physical
Transmitting data as bits over the physical medium (cable, fiber, radio signal). Voltage levels, cable types, etc.
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Data Link
Error-free data transfer between devices on the same physical network (frames). Physical addressing (MAC addresses).
Switches operate at this level. The Ethernet protocol resides here.
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Network
Routing of packets between different networks. Logical addressing (IP addresses) is performed at this level.
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Transport
End-to-end (host-to-host) data transfer that is reliable (TCP) or unreliable (UDP).
Error control, flow control. Port numbers are important for this layer.
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Session
Establishes connections between devices, tracks the active side, and performs synchronization.
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Presentation
Formats, encrypts, and compresses data, ensuring it reaches the application layer in a more understandable form.
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Application
The layer where applications interface with the network (HTTP, FTP, SMTP, DNS, etc.).
APIs operate here.
TCP/IP Model
A model created before the OSI model, focusing more on real-world applications.
It is named after its two most important protocols:
TCP (Transmission Control Protocol) and IP (Internet Protocol)
The most common 4-layer model:
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Application Layer
The layer where user applications interact with the network.
Roughly speaking, it combines the roles of the Application, Presentation, and Session layers in the OSI model.
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Transport Layer
Includes the TCP and UDP protocols.
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Internet Layer
IP ensures that data is routed between networks using IP packets.
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Network Access Layer (or Link Layer)
Determines how IP packets are routed over the network.
