How the Internet Works: Network Edge, Packet Switching, Routing, and the TCP/IP Stack

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The Internet is often described as a “network of networks,” and that phrase is still the best starting point. It is not one giant centralized system owned by a single company. It is a global collection of interconnected networks that communicate through standardized protocols. Cloudflare defines the Internet as a global network of interconnected computer networks that communicate using standard protocols, while the IETF’s original Internet Protocol specification describes IP as designed for interconnected packet-switched computer networks.

That design choice is what makes the Internet powerful. A phone on a mobile network in Manila can communicate with a server in Singapore, a CDN cache in Tokyo, a database replica in Oregon, or an API hosted on Google Cloud, AWS, or Azure because all these systems agree on common rules: IP addressing, routing, transport protocols, naming systems, and application protocols. The Internet works because independent networks can interoperate without being identical.

Internet Evolution

The Internet began as a research effort around packet-switched networking. Early ARPANET work showed that data could be split into packets and sent across shared infrastructure instead of requiring a dedicated circuit for every communication session. The transition from ARPANET’s earlier Network Control Protocol to TCP/IP in the early 1980s became a foundational moment in internetworking.

The World Wide Web came later. Tim Berners-Lee invented the Web at CERN in 1989, then wrote the first web client and server in 1990. W3C notes that his early specifications for URIs, HTTP, and HTML became the basis of the Web as it spread. This distinction matters: the Internet is the underlying network infrastructure; the Web is one major application built on top of it.

Since then, the Internet has evolved from academic and government networks into commercial broadband, mobile data, cloud computing, CDNs, streaming platforms, and edge infrastructure. Akamai describes CDNs as globally distributed edge servers that cache and deliver content closer to users to reduce latency, while Netflix’s Open Connect program localizes video traffic through ISP partnerships and embedded appliances.

1. The Network Edge

The network edge is where Internet communication starts and ends. It includes laptops, phones, desktops, smart TVs, IoT devices, enterprise workstations, cloud-hosted applications, and servers. In networking terms, these are often called end systems or hosts because they run applications such as browsers, email clients, web servers, APIs, streaming services, and mobile apps.

The modern edge is much broader than the old client/server model. A user’s phone may be a client when opening a website, but it can also upload video, stream live audio, sync files, run real-time messaging, or send telemetry from sensors. A server may live in a cloud region, a private enterprise data center, a CDN point of presence, or even inside an ISP network. Akamai describes edge servers as compute, storage, networking, and security resources placed closer to where data is produced and consumed.

This is why today’s Internet feels faster than a simple “user connects to distant server” model would suggest. Many requests no longer travel all the way to an origin server. They may terminate at a CDN, edge cache, reverse proxy, load balancer, security gateway, or regional cloud frontend. Cloudflare, Akamai, AWS, Google Cloud, Microsoft Azure, and Netflix all use some form of edge or backbone optimization to move traffic closer to users or keep it on high-performance private networks.

2. Access Networks

The access network is the part of the network that connects an end system to the first router or provider network on the path to the wider Internet. For a home user, this may be fiber, cable broadband, DSL, fixed wireless, Wi-Fi, or a home router connected to an ISP. For a business, it may be Ethernet, enterprise Wi-Fi, MPLS, SD-WAN, VPN, or a dedicated cloud interconnect. For mobile users, it is the cellular radio access network.

Home networks usually combine local connectivity and Internet access. Wi-Fi connects devices wirelessly to a router or access point, while Ethernet provides wired local connectivity. Cisco describes a wireless access point as a device that allows wireless-capable devices to connect to a wired network.

Institutional networks are more complex. Offices, schools, hospitals, factories, and government agencies often use switches, routers, access points, firewalls, identity systems, VPNs, VLANs, and monitoring tools. These networks do not merely “connect to the Internet”; they enforce access policies, segment traffic, prioritize applications, and secure internal systems.

Mobile access networks introduce another layer of complexity. Ericsson describes the 5G Radio Access Network as the link that connects wireless cellular devices to the core network, while Nokia describes the RAN as the final link between the network and the phone, including antennas, radios, and base stations.

In short, access networks are the Internet’s on-ramp. They decide the first part of the user experience: signal quality, bandwidth, congestion, latency, reliability, and sometimes whether traffic is routed efficiently at all.

3. Packet Switching at Global Scale

Once traffic leaves the access network, it enters the network core: a mesh of routers, backbone links, submarine cables, fiber routes, Internet exchange points, private cloud networks, and transit providers. The core does not send one continuous stream as a single object. It uses packet switching.

In packet switching, application data is broken into smaller units called packets or datagrams. Each packet carries addressing information that helps routers move it toward its destination. The IETF’s RFC 791 describes IP as transmitting blocks of data called datagrams from sources to destinations identified by addresses. Cloudflare similarly explains that data traversing the Internet is divided into packets, and IP information helps routers send those packets to the right place.

This design allows many users and applications to share the same infrastructure. Your video call, someone else’s banking transaction, another user’s Netflix stream, and a company’s API traffic may all share network links, but they are separated into packets and forwarded independently.

Packet switching is also why the Internet is resilient. Packets do not require one fixed end-to-end circuit. If routes change, congestion appears, or a link fails, routing systems can shift traffic to alternate paths. However, that flexibility also introduces complexity: packets may arrive out of order, experience delay, or get dropped. Higher-layer protocols such as TCP help applications recover from those conditions.

4. Forwarding vs. Routing

Routers perform two related but different jobs: forwarding and routing.

Forwarding is the local action. A packet arrives on one interface of a router. The router examines the destination IP address, checks its forwarding table, and sends the packet out through the appropriate next interface.