Glossary
The proxy glossary, without the fluff.
45 terms from across proxies, networking and web scraping, each defined in plain language and, where it matters, with the real-world detail that decides how the thing actually behaves. No dictionary glosses.
Proxy types
Datacenter proxy
A proxy whose IP address is hosted in a commercial data center rather than assigned to a home, making it fast and cheap but easy for sites to identify as non-residential.
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Dedicated proxy
A proxy IP address assigned to a single customer, so its reputation reflects only your own traffic.
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HTTP proxy
A proxy that understands the HTTP protocol and forwards web requests, optionally reading and modifying headers along the way.
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ISP proxy
A proxy hosted in a data center but registered to a consumer ISP, combining datacenter speed and stability with the trust of a residential network.
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Mobile proxy
A proxy that routes traffic through an IP address assigned by a mobile carrier to a phone or cellular modem, carrying the strongest trust of any proxy type.
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Open proxy
A proxy that accepts connections from anyone with no authentication, which is what almost every address on a free proxy list actually is.
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Residential proxy
A proxy that routes your traffic through an IP address assigned by an internet service provider to a home connection, so requests look like an ordinary person browsing.
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Rotating proxy
A proxy setup that assigns a different IP address to each request or on a timer, spreading traffic across a pool so no single address draws attention.
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Shared proxy
A proxy whose IP address is used by more than one customer at the same time, cheaper than a dedicated address but with reputation you do not fully control.
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SOCKS5 proxy
A proxy speaking the SOCKS5 protocol, which forwards any kind of TCP or UDP traffic without inspecting it, not just web requests.
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Static proxy
A proxy that keeps the same IP address for your exclusive use over an extended period, rather than rotating it between requests.
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Networking
ASN
An autonomous system number identifies the network that owns a block of IP addresses, and it is how sites tell a home connection from a data center.
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CGNAT
Carrier-grade NAT, the technique of putting many subscribers behind one shared public IP address to conserve scarce IPv4 space.
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DNS
The domain name system translates human-readable hostnames into IP addresses, and where that lookup happens can quietly expose your real location.
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DNS leak
When your DNS queries bypass the proxy and reveal your real network or location despite your visible IP being masked.
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Forward proxy
A proxy that sits in front of the client and forwards its outbound requests, the ordinary sense of the word proxy, as opposed to a reverse proxy that fronts a server.
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IP address
The numeric label that identifies a device on a network and is the address a proxy substitutes for your own.
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IPv4
The original internet addressing scheme, with about 4.3 billion possible addresses, now so scarce that providers ration and share them.
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IPv6
The newer addressing scheme with a practically unlimited supply of addresses, adopted unevenly across the world's networks.
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Port
A numbered channel on an IP address that directs traffic to a specific service, such as the port your proxy listens on.
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Reverse DNS
The lookup that turns an IP address back into a hostname, often the most telling single fact about who operates an address.
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Subnet
A contiguous block of IP addresses managed as a unit, often shared reputation and all.
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WebRTC leak
When a browser's real-time communication feature exposes your true IP address even though your traffic runs through a proxy.
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Protocols & authentication
IP whitelisting
Authorising a proxy by pre-approving the IP addresses allowed to use it, instead of sending a username and password.
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Proxy authentication
How a proxy verifies you are allowed to use it, most commonly by username and password or by allowing specific source IPs.
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Reverse proxy
A proxy that sits in front of servers rather than clients, handling incoming requests on their behalf, the opposite direction from the forward proxies used for scraping.
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SOCKS4 proxy
An older version of the SOCKS protocol that relays TCP traffic but lacks authentication, UDP support and remote DNS.
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Sticky session
A rotating-proxy feature that keeps you on the same exit IP for a set duration so a multi-step task can complete without the address changing underneath it.
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Scraping & automation
Browser fingerprinting
Identifying a visitor from the combination of subtle browser and device traits, a layer of detection that survives changing your IP.
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CAPTCHA
A challenge designed to tell humans from bots, triggered far more often by suspicious network reputation than by any single request.
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Geo-blocking
Restricting or changing what a site shows based on the visitor's inferred country, which a proxy in the target country is meant to bypass.
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Geo-targeting
Deliberately choosing a proxy in a specific country, region or city so your traffic originates exactly where you need it to.
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IP rotation
The practice of cycling through many IP addresses across a workload so no single one accumulates a suspicious request count.
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Rate limiting
A site's cap on how many requests one source may make in a window, the most common obstacle a scraper meets.
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User agent
The string a client sends to identify its browser and operating system, one of the simplest signals a site checks against your IP.
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Web scraping
The automated collection of data from websites, the single most common reason people use proxies at scale.
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Detection & reputation
Fraud score
A single number that fraud-detection services assign to an IP address to summarise how risky traffic from it looks.
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IP blacklist
A published list of IP addresses flagged for abuse, which sites and mail servers consult to refuse traffic outright.
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IP reputation
The accumulated trust score a site or third-party service assigns to an IP address based on its network, history and behaviour.
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Port scanning
Probing an address across many ports to find services that answer, which is how most public proxy lists are assembled in the first place.
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Proxy detection
The set of techniques sites use to decide whether a visitor is behind a proxy, ranging from network lookups to behavioural analysis.
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X-Forwarded-For
An HTTP header a proxy can add to name the original client's IP, and the single biggest tell that separates an anonymous proxy from a transparent one.
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Performance
Bandwidth
The volume of data a proxy can move, and the unit residential and mobile proxies are typically billed by.
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Latency
The delay between sending a request through a proxy and getting a response, driven largely by physical distance to the exit.
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Uptime
The share of time a proxy is actually reachable and working, which for residential pools is a live measurement rather than a guarantee.
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