HTML is a markup language that is used by the browser to manipulate text, images, and other content to display in the required format.

HTML helps to structure our website well. The way a skeleton system gives a structure to the human body in a similar manner HTML acts as a skeleton for a website, without it a website cannot be made. If you want to work as a Software Developer especially in the Web Development domain, then learning HTML is a must, because without knowledge of it you cannot build a website.
Base for creating websites: HTML is the basic necessity a developer should know while building a website from scratch.
Learn web development: HTML is the first step towards learning Web Development. Once you learn HTML, you can build simple, static websites very easily.
Can become freelancer: Since web development has the best scope in freelancing, therefore learning HTML will surely help you to get the best deals of website development in the market.

HTML Form is a document which stores information of a user on a web server using interactive controls. An HTML form contains different kind of information such as username, password, contact number, email id etc. The elements used in an HTML form are check box, input box, radio buttons, submit buttons etc. Using these elements the information of an user is submitted on a web server. The form tag is used to create an HTML form.

This is the document type declaration (not technically a tag). It declares a document as being an HTML document. The doctype declaration is not case-sensitive.
"html": This is called the HTML root element. All other elements are contained within it.
"head": The head tag contains the “behind the scenes” elements for a webpage. Elements within the head aren’t visible on the front-end of a webpage. HTML elements used inside the "head" element include:
- style
- title
- base
-noscript
-script
- meta
- link
"body": the body tag is used to enclose all the visible content of a webpage. In other words, the body content is what the browser will show on the front-end.
An HTML document can be created using any text editor. Save the text file using .html or .htm. Once saved as an HTML document, the file can be opened as a webpage in the browser.
NOTE: Basic/built-in text editors are Notepad (Windows) and TextEdit (Macs). Basic text editors are entirely sufficient for when you’re just getting started. As you progress, there are many feature-rich text editors available which allow for greater function and flexibility.

CSS (Cascading Style Sheets) is a stylesheet language used to design the webpage to make it attractive.
The reason of using CSS is to simplify the process of making web pages presentable.
CSS allows you to apply styles to web pages. More importantly, CSS enables you to do this independent of the HTML that makes up each web page. There are three types of CSS which are given below:
Inline CSS
Internal or Embedded CSS
External CSS

Styling has been an essential property for any website since many decades.
It increases the standards and overall look of the website which makes it easier for the user to interact with it.
A website cannot be made without CSS, as styling is MUST since no user would want to interact with a dull and shabby website.
So for knowing Web Development, learning CSS is must.
Base for web development: HTML and CSS is the basic skill that every web developer should know. It is the basic skill that is required for building a website.
Makes your website look attractive: A website that’s dull and plain will not attract the user most probably, so adding some style would surely make your website presentable to the user.
Makes the design come live: A web developer is responsible in making the design given to him as a live product. CSS is used for styling to develop the design of the website.
Increases user experience of website: A website with a simple yet beautiful UI would help the users to go through the website easily. CSS is used to make the user interface better.
More career opportunities: Since CSS is a basic requirement while learning Web Development, therefor there are abundant career opportunities for it. As a freelancer too you can land up to many projects.

A CSS ruleset is various affirmations to various pieces or elements of the document.
The objective is to apply a bunch of properties for certain distinct qualities to a solitary, or a particular arrangement of components in the connected HTML page.

Advantages of using CSS: 1. CSS helps you save time: CSS can be written once and then reused in multiple HTML pages. You can define a style for each HTML element and apply it to an unlimited number of Web pages.
2. Results in less code: We use less code because we define the property with a value in a common style class and use the same class in multiple places. Less code means less bandwidth consumption and easier content maintenance.
3. Easy maintenance: Because we define styles globally or in a common location, any changes are simple. For example, on a website, all of the product names are displayed using a specific style property. We can now change the style throughout the site by changing the style class at the external style sheet for the product name. We can keep multiple style sheets and use them based on the situation. The use of property inheritance methods made it simple to maintain multiple styles of the same tag.
4. Web standards around the world: HTML attributes are now deprecated, and CSS is recommended instead. As a result, it’s a good idea to start using CSS in all HTML pages to ensure compatibility with future browsers.
5. Pages are downloaded quickly: Because browsers cached the style sheet page, page loading became faster. When different pages of the same site use the same CSS, the styles classes are not loaded from the server.

JavaScript is the world most popular lightweight, interpreted compiled programming language.
It is also known as scripting language for web pages.
It is well-known for the development of web pages, many non-browser environments also use it.
JavaScript can be used for Client-side developments as well as Server-side developments.

Internal JS: We can add JavaScript directly to our HTML file by writing the code inside the "script" tag. The "script" tag can either be placed inside the "head" or the "body" tag according to the requirement.
External JS: We can write JavaScript code in other file having an extension .js and then link this file inside the "head" tag of the HTML file in which we want to add this code.

JavaScript is a widely-used programming language. Given below are some domains/products that can be built using JavaScript:
1. Websites: JavaScript helps us to add behavior of our website. It helps users to interact with the website. For eg. clicking on buttons, saving details, uploading details on the website, etc.
2. Web Servers: We can make robust server applications using JavaScript. To be precise we use JavaScript frameworks like Node.js and Express.js to build these servers.
3. Game Development: In Game Development industry, JavaScript is used widely. With the addition of HTML5 Canvas, it’s now possible to make 2D and 3D games in JavaScript very efficiently.
4. 3D Drawings: JavaScript in addition with HTML Canvas is used to make three-dimensional graphics.
5. Mobile Apps: Mobile applications are the most popular modes of communicating these days. JavaScript also used to design mobile applications. There are many JavaScript frameworks using which we can make android, IOS, and hybrid apps.
6. Smartwatch Apps: The popular smartwatch maker Pebble has created Pebble.js, a small JavaScript framework that allows a developer to create an application for the Pebble line of watches in JavaScript.

avaScript is the most popular and hence the most loved language around the globe. Apart from this, there are abundant reasons to learn it. Below are a listing of few important points:
1. No need of compilers: Since JavaScript is an interpreted language, therefore it does not need any compiler for compilations.
2. Used both Client and Server-side: Earlier JavaScript was used to build client-side applications only, but with the evolution of its frameworks namely Node.js and Express.js, it is now widely used for building server-side applications too.
3. Helps to build a complete solution: As we saw, JavaScript is widely used in both client and server-side applications, therefore it helps us to build an end-to-end solution to a given problem.
4. Used everywhere: JavaScript is so loved because it can be used anywhere. It can be used to develop websites, games or mobile apps, etc.
5. Huge community support: JavaScript has a huge community of users and mentors who love this language and take it’s legacy forward.