Understanding the Differences Between HTTP GET and POST Methods
This article explains the fundamental similarities and practical differences between HTTP GET and POST requests, covering how parameters are transmitted, caching behavior, URL length limits, security considerations, underlying TCP mechanics, and the impact on performance and semantics.
GET and POST are the two basic HTTP request methods; the most intuitive difference is that GET includes parameters in the URL while POST sends them in the request body.
The commonly cited "standard answer" lists differences such as GET being safe for browser back navigation, bookmarkable URLs, cacheable by default, limited to URL encoding, visible in history, subject to URL length limits, and less secure because parameters appear in the URL.
GET is harmless on browser back navigation, POST may resubmit.
GET URLs can be bookmarked; POST cannot.
GET requests are cached by browsers by default; POST is not unless manually configured.
GET only supports URL‑encoded data; POST supports multiple encodings.
GET parameters remain in browser history; POST parameters do not.
GET URLs have length limits; POST does not.
GET accepts only ASCII characters; POST has no such restriction.
GET is less secure because parameters are exposed in the URL.
GET sends parameters via URL; POST places them in the request body.
Both methods operate over TCP/IP, so technically they are equivalent TCP connections; the distinction lies in how HTTP specifies the placement of data (URL vs. body) and how browsers/servers enforce limits.
Browsers typically limit URL length to about 2 KB and servers often accept up to 64 KB; exceeding these limits can cause requests to be rejected.
Although GET can technically include a request body, many servers ignore it, so relying on that behavior is unsafe.
In practice, GET usually results in a single TCP packet (header + data) while POST often involves two packets: an initial header exchange (100 Continue) followed by the data packet, which can add latency.
However, this packet‑count difference is minor in good network conditions, and some browsers (e.g., Firefox) send POST in a single packet.
Therefore, while GET and POST share the same underlying capabilities, HTTP conventions, browser and server constraints, and semantic meanings lead to the practical differences developers must consider.
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