What Is an ISP

An ISP (Internet Service Provider) is a company that provides internet access to homes and businesses. When you browse the web, your data first travels to your ISP's network, which then routes it to servers around the world. ISPs handle essential functions including IP address assignment, DNS server provision, and traffic routing. Without an ISP, connecting to the internet is simply not possible.

Major ISPs vary by country. In the US, providers like Comcast, AT&T, and Verizon dominate the market. In Japan, NTT, KDDI, and SoftBank are the leading providers. The ISP landscape in each region is shaped by the available physical infrastructure and regulatory environment.

Connection Types Compared

Uses fiber optic cables directly to the premises. Offers speeds of 1-10 Gbps with low latency. The gold standard for home internet, though availability depends on infrastructure buildout in your area.

Uses existing coaxial cable TV infrastructure. Download speeds of several hundred Mbps are common, but upload speeds are often limited. Shared bandwidth with neighbors can cause slowdowns during peak hours.

Wireless connection via cellular networks. No installation required, making it ideal for temporary setups. Speed varies significantly based on signal strength and network congestion. Available as portable hotspots or fixed wireless home units.

Uses copper telephone lines. Once the dominant technology, now largely superseded by fiber. Speed degrades with distance from the exchange. Most providers have stopped accepting new DSL subscriptions.

How to Choose an ISP

Comparing ISPs solely on advertised maximum speeds is misleading. Real-world performance depends on network congestion, infrastructure quality, and your specific location. Consider these factors:

Real-world speed during peak hours: Evening hours (8-11 PM) are when networks are most congested. ISPs that support IPv6 with modern routing protocols tend to handle congestion better.
Total cost: Look beyond the monthly fee. Factor in installation costs, equipment rental, early termination fees, and whether promotional pricing expires after a set period.
Reliability and uptime: Check outage history and how quickly the ISP communicates about service disruptions. Business-grade plans typically offer better uptime guarantees.
Contract terms: Some ISPs lock you into 1-2 year contracts with steep cancellation penalties. Month-to-month options provide flexibility at a slightly higher monthly cost.

ISP and Privacy - What Your Provider Can See

Your ISP sits between you and the internet, which means it can technically observe which domains you connect to and when. Even with HTTPS encryption, the destination domain name (via SNI) remains visible to your ISP. The actual page content and form data are encrypted and unreadable.

ISPs in most countries are legally required to protect communication privacy. However, they must comply with lawful data requests from law enforcement agencies with proper court orders. Some jurisdictions also require ISPs to retain connection logs for a specified period.

To minimize what your ISP can observe:

Use a VPN to encrypt all traffic, so your ISP only sees a connection to the VPN server
Enable DNS over HTTPS (DoH) to prevent your ISP from seeing your DNS queries
Switch from your ISP's default DNS to a privacy-focused public DNS like Cloudflare (1.1.1.1)

ISP and IP Address Assignment

When you connect to the internet, your ISP assigns a public IP address to your connection. This address is what websites see when you visit them, and it is the address displayed on our homepage.

IP address assignment varies by ISP. Some provide static addresses that remain constant, while others use dynamic assignment where your address may change periodically. GeoIP databases can identify your ISP and approximate geographic location from your IP address, but they cannot determine your physical street address without a legal disclosure request to the ISP.

With IPv6 adoption, some ISPs use CGNAT (Carrier-Grade NAT) to share a single IPv4 address among multiple subscribers. This makes it harder to identify individual users by IP address alone, but can also cause issues with services that rely on IP-based identification.

Common Misconceptions

Switching ISPs will always make your internet faster: ISP changes only improve the provider-side network quality. If the bottleneck is your Wi-Fi setup, router performance, or building wiring, changing ISPs won't help. Always test with a wired connection first to isolate the cause of slow speeds.
Your ISP monitors everything you do online: With HTTPS now standard on most websites, ISPs can only see which domains you connect to and how much data you transfer. The actual page content, search queries, and form submissions are encrypted. However, unencrypted DNS queries do reveal your browsing destinations unless you use DNS over HTTPS.
All fiber ISPs deliver the same speed: Even on the same physical fiber network, ISPs differ in backbone capacity and infrastructure investment. During peak evening hours, speed differences between ISPs can be dramatic. Whether an ISP supports IPv6 with modern routing also significantly affects real-world performance.

ISP (Internet Service Provider)