Site Info - Stepik.org

Tilda is a hosted website builder.

Zendesk provides hosted customer service software.

PHP is a scripting language for creating websites.

Ruby is a general-purpose object-oriented language originally developed by Yukihiro "Matz" Matsumoto in Japan.

JavaScript is a lightweight, object-oriented, cross-platform scripting language, often used within web pages.

jQuery is a JavaScript library that simplifies HTML document traversing, event handling, animating and Ajax interaction. Originally developed by John Resig.

KaTeX is a JavaScript library for math typesetting.

Materialize is a responsive front-end framework based on material design.

Nginx (pronounced as "engine X") is a lightweight open source web server developed by Igor Sysoev.

The Apache HTTP Server is an open source web server by the Apache Software Foundation.

Tilda is a hosted website builder.

Host Europe is a German web hosting provider owned by GoDaddy Group.

Selectel is a Russian data center operator.

Zendesk provides hosted customer service software.

Host Europe is a German web hosting provider owned by GoDaddy Group.

Selectel is a Russian data center operator.

Tilda is a hosted website builder.

Qrator provides DDoS protection and other network services.

DDoS-Guard provides DDoS protected services.

GoDaddy is a provider of internet services. This includes the former brand Media Temple.

Cloudflare provides DNS servers and other web services.

Yandex is a Russian provider of internet-based services.

Let’s Encrypt is a free, automated, and open certificate authority provided by the Internet Security Research Group.

The validity of the SSL certificate has expired.

The CDNJS is a content distribution network, hosting a large number of JavaScript libraries, provided by CloudFlare.

Google Analytics is a free service to get detailed statistics about the visitors of a website, provided by Google. This includes the Ads conversion tracking and the Floodlight services.

Yandex.Metrica is a free web analytics system combining customizable reporting tools with behavioral analytics.

Amplitude provides a product data analytics, including web analytics platform.

The Google Tag Manager is a Google service to support webmasters to manage tags on their websites.

External Cascading Style Sheets define style rules in a separate CSS file.

Embedded Cascading Style Sheets define a set of style rules in a <style> element within a web page.

Inline Cascading Style Sheets define style rules directly within an (X)HTML element using the style attribute.

Persistent cookies with an expiration time of up to 1 day.

Persistent cookies with an expiration time between 1 month and 1 year.

HttpOnly cookies are used only in the HTTP protocol and not in client side scripts, which may increase security.

Non-HttpOnly cookies are used in the HTTP protocol and also in client side scripts, which may be a security threat.

Secure cookies are used only via an encrypted connections, which may increase security.

Non-secure cookies may be used via an unencrypted connections, which may be a security threat.

Brotli is a lossless compression algorithm developed by Google.

Gzip (GNU zip) is a file compression algorithm.

A strong ETag is an HTTP header field for validation of cached web pages, that indicates a byte-for-byte identical page in the cache.

HTTP/2 is the second major version of the HTTP network protocol.

HTTP Strict Transport Security (HSTS) defines a mechanism enabling web sites to declare themselves accessible only via secure connections.

The websites redirects visitors to use SSL encryption, e.g. from http://example.com/ to https://example.com/.

The Open Graph protocol, originally developed by Facebook, is an RDFa-based format that enables any web page to become a rich object in a social graph.

Twitter/X Cards enable automatic attachment of photos, videos and media elements to tweets.

JSON-LD (JavaScript Object Notation for Linked Data) is a method of encoding Linked Data using JSON.

Microdata is a specification to integrate metadata within existing content on web pages.

HTML5 is the fifth revision of the HTML standard.

UTF-8 (8-bit Unicode Transformation Format) is a variable-length character encoding for Unicode, which is backwards compatible with ASCII.

PNG (Portable Network Graphics) is a lossless compression image format, suitable to store graphics with uniformly colored areas, and originally introduced as a free, open-source successor of GIF.

JPEG (Joint Photographic Experts Group) is a lossy compression method suitable to store photographic images.

Scalable Vector Graphics (SVG) is an XML-based vector image format.

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