Web Widget Glossary
Plain-English definitions of essential terms in web embeds, JavaScript widgets, APIs, and SaaS integrations. From iFrames to webhooks — everything you need to know.
iFrame
An iFrame (inline frame) is an HTML element that embeds another webpage inside the current page. It creates a separate browsing context, isolating the embedded content from the parent page. iFrames are commonly used to embed maps, videos, payment forms, and third-party widgets.
Read definition →Embed Code
Embed code is a snippet of HTML, JavaScript, or a combination of both that you copy from a third-party service and paste into your website to display external content. It can be as simple as an <iframe> tag or as complex as a multi-line JavaScript loader that injects a widget at runtime. Embed codes power everything from social media feeds to interactive widgets and payment forms.
Read definition →Shadow DOM
Shadow DOM is a web standard that allows a component to encapsulate its own HTML structure, styles, and behavior — completely isolated from the main document. Styles defined inside a Shadow DOM do not leak out, and styles from the host page cannot leak in. It is the technology that makes truly portable, style-safe web widgets possible.
Read definition →HTML Snippet
An HTML snippet is a small, self-contained piece of HTML code that can be inserted into a webpage to add a specific element or functionality. Unlike full HTML documents, snippets are partial code fragments — such as a contact form, a banner, or a button — designed to be dropped into an existing page without breaking its structure.
Read definition →CTA Button
A CTA (Call-to-Action) button is an interactive UI element designed to prompt a specific user action — such as signing up, downloading, or purchasing. It is typically the most visually prominent element on a page, using contrasting colors, action-oriented copy, and strategic placement to drive conversions. CTA buttons are the single highest-leverage element in conversion rate optimization.
Read definition →CSS Selector
A CSS selector is a pattern used to target and style specific HTML elements on a webpage. Selectors can target elements by tag name, class, ID, attribute, position in the DOM, or combinations thereof. Mastering CSS selectors is fundamental to both styling web pages and using JavaScript APIs like document.querySelector().
Read definition →Webhook
A webhook is an HTTP callback that sends real-time data from one application to another when a specific event occurs. Unlike polling — where you repeatedly ask a server "did anything happen?" — a webhook pushes data to your endpoint the moment an event is triggered. Webhooks are the backbone of modern event-driven integrations between web services.
Read definition →API Key
An API key is a unique alphanumeric string used to authenticate requests to an API (Application Programming Interface). It identifies the calling application and grants access to the API's resources. API keys are among the most common authentication methods for web services, developer tools, and SaaS platform integrations.
Read definition →Shortcode
A shortcode is a small piece of text in square brackets — like [contact-form] or [pricing-table id="3"] — that a CMS such as WordPress replaces with actual HTML when rendering a page. Shortcodes act as macros: they are simple placeholders that trigger the generation of complex output. They are the primary way WordPress plugins embed dynamic content into post and page content.
Read definition →JavaScript Widget
A JavaScript widget is a self-contained, interactive UI component that is embedded into a third-party website via a JavaScript snippet. Unlike static HTML or iFrame embeds, JavaScript widgets can dynamically render content, respond to user interactions, communicate with APIs, and adapt to the host page's context. They are the modern standard for embeddable third-party functionality.
Read definition →Ready to embed your first widget?
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