VPNs: How They Work and Why You Should Use One

You've certainly heard about them: VPNs have become one of those tools that even non-technical people have started using. But what do they actually do? When are they useful and when are they just an unnecessary cost? And above all: are all VPNs equal? In this guide we explain everything clearly, without oversimplifying.

What is a VPN?

VPN stands for Virtual Private Network. In practice it's an encrypted tunnel between your device and a remote server: all internet traffic passes through this tunnel before reaching its destination.

The result:

1. Your real IP address is hidden — websites see the VPN server's IP, not yours
2. Traffic is encrypted — no one on the local network (not even your ISP) can see what you're doing
3. Your apparent geographic location changes — you can appear to be connected from another country

How does it work technically?

When you activate a VPN, your device establishes an encrypted connection with the VPN server using a specific protocol (WireGuard, OpenVPN, IKEv2 are the most common today). From that moment:

• Every data packet leaving your device is encrypted locally before it even leaves your Wi-Fi network
• The packet travels encrypted to the VPN server
• The VPN server decrypts the packet and sends it to the real destination (the website, the service, etc.)
• The response goes back to the VPN server, which encrypts it and sends it back to you

For the destination website, the request appears to come from the VPN server's IP address, not yours.

When a VPN is truly useful

Public Wi-Fi: airports, hotels, cafes

Public Wi-Fi networks are not encrypted. Anyone connected to the same network can potentially intercept your traffic with very simple tools. A VPN makes all traffic unreadable, even on these networks.

Remote work and access to company resources

Most companies use VPNs to allow remote employees to access internal resources (file servers, business management systems, intranet) as if they were physically in the office. In this case a VPN is not a choice but a requirement.

Privacy from your ISP

Your ISP technically sees all the traffic that passes through its network. In many countries ISPs don't sell this data, but with a VPN your traffic becomes opaque even to them.

Access to geo-blocked content

Netflix US has a different catalog from Netflix in other countries. By connecting to a VPN server in the United States, the service sees you as an American user. The same applies to sports events, regional streaming services, or sites with geographic restrictions.

Protection on shared networks

Universities, hostels, shared offices: every time you use a network you don't control, unencrypted traffic is exposed. A VPN protects you in these environments too.

When a VPN is not needed (or doesn't help)

A VPN is not:

• An antivirus: it doesn't protect you from malware, phishing, or dangerous links
• Total anonymity: Google, Facebook, and others track you through cookies and accounts, not just by IP
• A solution to speed problems: in fact, a VPN adds latency; if your connection is slow, it won't improve anything
• Protection from sites with HTTPS: most modern web traffic is already encrypted by the browser

VPN protocols: the differences

The protocol determines speed, security, and compatibility:

| Protocol | Pros | Cons | |----------|------|------| | WireGuard | Very fast, simple and auditable code | Relatively new | | OpenVPN | Mature, very secure, widely supported | Complex configuration, slower | | IKEv2/IPSec | Excellent on mobile, reconnects quickly | Difficult to configure independently | | L2TP/IPSec | Supported everywhere | Considered less secure, slow |

WireGuard is today the recommended protocol for new installations: it's faster than OpenVPN, has a source code of just ~4,000 lines (compared to OpenVPN's 400,000+) — much easier to audit for vulnerabilities.

Commercial VPN providers: what to evaluate

If you don't want to manage your own server, you can use a commercial VPN provider. Criteria for choosing one:

• Zero-log policy: the provider must not keep records of your traffic. Look for those that have undergone independent audits
• Protocol used: prefer WireGuard or OpenVPN
• Jurisdiction: a provider headquartered in a country with strong privacy laws (Switzerland, British Virgin Islands, Panama) is preferable
• Kill switch: if the VPN drops, traffic must be automatically blocked, not go out "in the clear"
• Speed and number of servers: more available servers, more choice on location

Among the most reliable providers verified by independent audits are Mullvad, ProtonVPN, and IVPN — all with verified no-log policies and headquartered in privacy-friendly countries.

Self-hosted VPN: the alternative for those with a server

If you have a VPS or dedicated server, you can install your own VPN with WireGuard. The advantage is total control: your data doesn't pass through anyone else's server. The limitation is that you have a single node (the server you chose) and you need to handle maintenance.

For a step-by-step guide to installing WireGuard on Debian 12, read our dedicated article: Installing WireGuard Server on Debian 12.

Frequently asked questions

Is using a VPN legal? Yes, absolutely. Using a VPN is perfectly legal. What is illegal remains illegal even with a VPN: the means does not change the nature of the action.

Does a VPN slow down the connection? Yes, by a small amount. Encryption and the extra route introduce latency. With modern protocols like WireGuard on nearby servers, the slowdown is often under 10%. On fiber with European servers, it's rarely noticeable.

Can I use a free VPN? They exist, but with serious limitations: limited bandwidth, a reduced number of servers, and they often collect user data (which is exactly what you want to avoid). For serious use, it's worth spending a few dollars a month for a reliable service.