Cascading styles sheets are a language used most commonly to separate the document content of an HTML or XHTML file from the presentation. This allows you to separate such things as the layout, colors, fonts and more from the main HTML file or change the attributes within the file.
There are three types of styles when it comes to CSS. The first of the three styles would be inline styles. Next would be embedded styles and last would be external styles. There are many different advantags and disadvantages to using each different style. Each web designer has their own preference and sometimes even different reasons as to why they prefer specific style.
Inline styles are written directly into the tag on the document and affect only the tag that they are applied to. Embedded styles, on the other hand, are embedded in the head of the document and affect only the tags that they are embedded in. External styles are written in a separate document and attached to a web document or various documents. The external sheets affect all documents that they are attached to.
In my opinion the best style to use is the external style CSS. The main reason is because having them on an external file makes them easier to maintain as well as being more friendly for search pages.
The disadvantage of using external CSS is that it is not on the same file as the rest of your web page, so could be lost or forgotten easily.
Inline styles work well because you can apply them only to the tags that you want them to affect. The down side of this is that if you want them applied to a lot of different tags, you have to manually input them into every tag.
Embedded styles are added to the head of the document and affect whatever tags they are then embedded into. This makes using them easy and keeps it all on the same HTML or text document. The downsize is that you then have a larger size of HTML, making errors and changes...