A basic understanding of HTML code can go a long way when working on your website. HTML code is simply a language that provides a set of instructions that web browsers (Internet Explorer, Firefox, Safari, etc.) use to display content/webpages. It is primarily made up of two parts - plain text and tags.
The plain text portion of HTML code is simply the content, or the portion that a web browser actually displays on the page. Every bit of content/text you see on this page is actually un-formatted, plain text in the background. It's your web browser that translates everything into what you see on the screen.
In order for your browser to display content, it needs some basic instruction. These instructions are provided in the HTML code and are called tags. A tag is made up of angle brackets ("<" and ">") with an element (the instruction) in between. Most HTML elements require a starting tag (ex: <p>) and an ending tag (ex.: </p>) which is simply the starting tag with a / at the beginning. Take a look at the examples below; the HTML tags are shown to you in bold to make it easier.
<p>This example shows a few more HTML tags in use. Bold and italics are both common HTML elements and are very easy to accomplish with code. <strong>Bold text uses these tags</strong> and <em>italics uses these tags</em>.
<h1>Headings are also very common</h1>
<h2>Heading 2 Example</h2>
<h3>Heading 3 Example</h3>
Headings are often used on pages for titles and to create different sections. For example, on this page you can see the text "Plain Text" and "Tags" stands out above - this was accomplished by indicating that they are heading 2 text.
Many pages can be created with only the few simple tags discussed above. There are of course many more tags and elements that are used in HTML - to see more try doing a web search for "HTML tags".