301 Redirect
A 301 redirect is a permanent HTTP status code that automatically forwards users and search engines from one URL to another...
400 Bad Request
Severity: Minor · Fix time: Under 5 min · Skill level: BeginnerA 400 Bad Request is an HTTP status code indicating that the server could not process a request because what was sent didn't make sense — malformed syntax, an invalid URL, oversized data, or corrupted cookies...
401 Unauthorized
Severity: Major · Fix time: 5–15 min · Skill level: BeginnerA 401 Unauthorized is an HTTP status code indicating that a request could not be completed because valid authentication credentials were not provided...
403 Forbidden
Severity: Major · Fix time: 5–15 min · Skill level: Intermediate403 Forbidden is an HTTP status code returned by a web server when a request is understood but deliberately refused...
404 Error
Severity: Minor · Fix time: Under 5 min · Skill level: BeginnerA 404 Error is an HTTP status code that a web server returns when it cannot find the requested page or resource at the given URL...
500 Internal Server Error
Severity: Critical · Fix time: 15–60 min · Skill level: IntermediateA 500 Internal Server Error is an HTTP status code indicating that something went wrong on the web server while trying to fulfill a request, but the server couldn't identify what specifically failed...
502 Bad Gateway
Severity: Critical · Fix time: 5–15 min · Skill level: IntermediateA 502 Bad Gateway is an HTTP status code that appears when a server acting as a gateway or proxy receives an invalid, corrupted, or unintelligible response from an upstream server...
503 Service Unavailable
Severity: Critical · Fix time: 15–60 min · Skill level: Intermediate503 Service Unavailable is an HTTP status code indicating that a web server is temporarily unable to handle a request...
Above The Fold
Above the fold refers to the portion of a webpage that is visible in the browser window when the page first loads — before the visitor scrolls down...
Accessibility
Accessibility in web design refers to the practice of building websites and digital experiences that can be used by people with disabilities — including those with visual, auditory, motor, and cognitive impairments...
