Sure. Most web pages use HTML, hypertext markup language, to add formatting to standard text. For example, you can use tables, colors, bold/italic fonts, etc.

If you want to do anything beyond the scope of that, you need a scripting language such as DHTML or JavaScript, for example.

Dynamic Drive is the only site I know of that suppliies free DHTML code snippets. Unfortunately, I don't know the language myself.

If you could provide us with an example of where you've seen what you're asking for, I could help further. You mentioned you saw it here, at TechTalkForums? Perhaps you're referring to a blinking cursor inside a textbox where you type? (A blinking text I-beam inside a textbox is a standard Windows feature).