What is HTML and CSS?

This is M, our data scientist. In this issue, I will provide information related to the most basic of digital implementation: website creation. Instead of promoting products and services through human sales, the basic concept in websites is to gain online recognition and attract customers.


HTML and CSS are a type of programming language and are generally popular languages for building websites.

In the process of coding these languages to build websites and other products, you can be particular about design and functionality, and you can reproduce everything from the design comps and structure in detail.

Naturally, experience and in-depth knowledge are necessary to improve the quality of website design and functionality.

On the other hand, a CMS can be developed smoothly even without deep expertise by preparing a minimum knowledge of HTML and CSS, or a CMS with an excellent user interface in a development environment can create a site by drag-and-drop visualization of images and contents. I would like to mention CMSs and other such systems at a later date, but the fact is that today, with the increasing trend toward in-house IT and digital production, a wide variety of great CMSs are in widespread use.

What is HTML?

Now, the most important features of HTML are markup and hypertext. Markup indicates the structure of the text and the role of the text by enclosing parts of the text in brackets called tags. Markup is used to convey information to computers in an easy-to-understand manner and to humans via browsers such as Google Chrome, Microsoft Edge, Firefox, etc. Hypertext is a type of text that is used when browsing websites.

Hypertexts are the buttons and blue links you see when browsing websites. This feature allows you to go back and forth to various pages and search for information.


The most important feature of CSS is that it is a programming language that sets the design that governs the look and feel of a website.

Common examples of what can be done with CSS include text color, text size, background image and background color, and the placement of text and images.

While HTML only serves as the framework of the site, CSS is a very important function for users who visit the site and view the pages, as it affects the "likes and dislikes" of the site and its "visual oldness or newness.

From a development perspective, there are two major ways to write CSS: one is to write directly into the HTML syntax, and the other is to create a separate CSS file that is independent of the HTML file. In the latter case, the CSS file is loaded as a file external to the HTML.

For example, if you are only creating one page (index.html) and do not plan to update the file in the future, the first method of writing directly into the file may be considered, but in most cases, the second method is the most common.

In general, it is necessary to create multiple pages for a simple website, and it is not efficient to write the same CSS syntax in an HTML file every time to make the layout the same, so it is more convenient to read CSS as an external file. Therefore, it is more convenient to load CSS as an external file.

In addition, CSS can be created as an independent file for maintenance, which allows for efficient editing without mistakes or omissions.

How is CSS reflected in the design?

When designing text size and color with CSS, it is possible to specify which tag to design for by specifying attributes such as class to mark the target tag.

However, many people think that there is no problem with using "id" because it is also possible to specify the design by specifying "id" as well. However, mixing class and id without thinking at all and using them in conjunction with CSS increases the risk of problems in creation.

When creating a large or complex site, there are many opportunities to make the site redundant by using javascript in addition to HTML and CSS. javascript, like CSS, can be input directly into HTML or imported as an external file. In the case of javascript, it is not possible to apply javascript without specifying an id, so an id that was intended to be specified in CSS may end up being applied as javascript.

While HTML plays a role in the overall framework of a website, if there is a problem with the framework, no matter how much effort is put into the CSS design, it will not be expressed and will be wasted. This is why coding checks are so important.

One method of coding check is the W3C HTML Checker, a website for checking coding. Using this checker is similar to debugging in general programming, and it prevents the omission of parentheses in tags and the forgetting of closing tags, which are often overlooked.

There are various coding checkers other than "W3C HTML Checker," but "W3C HTML Checker" has the advantage that it can be used free of charge on the site.

The general flow is to create a website using HTML and CSS and complete it using a coding checker, but in recent years, with the spread of smartphones and tablets, websites are being accessed through a variety of information media.

Therefore, it has become necessary to create sites that take into account the screen sizes of smartphones and tablets, rather than creating sites only for PCs, as in the past. Companies that only create sites for PCs and service businesses that can only provide such sites will be weeded out without attracting attention from anyone.

This is where the concept of responsive design comes in. Responsive design refers to the redundancy of screen design according to the information medium in which the site is viewed. As the name "responsive design" suggests, CSS is set to change the design in a responsive manner. Responsive design can change the screen display for each device, and since only one HTML and CSS file is needed for each device, it is easy to manage and can be accessed from a variety of devices, which can be expected to increase the number of visitors.

On the other hand, if the website is not designed to be accessed by small devices such as smartphones, the access speed may be slow. Therefore, if the design is too elaborate, the access speed may be affected when accessed from smartphones.

In light of the above, as various information media are likely to be created in the future, the number of jobs creating websites using HTML, CSS, etc. is expected to increase. In fact, if you look up job openings for website creation projects, you will find many that require responsive design.

While keeping in mind the three points to consider when creating a website, by combining CMS and creation tools with HTML and CSS, it is possible to create an efficient website by using CMS and creation tools to create the general scope of the base, and then using HTML and CSS to create the detailed design and functions beyond that. This leads to more efficient creation and easy-to-use websites.

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