Anyone can tell me someting about "tag"

Now our site want to use "tag", And our site is an B2C website,so we sale electronics gadgets online, but i do not know how to do it,and i do not know what is the effect of "tag", anyone can tell me?Or could you show me serveal sites had used this function?
Thanks.

 

Tag is a term which is generally used with keyword, it will help visitors to find your sites easily.You should always use tags relevant to your sites ,you can use many free tools to create tag for your sites.

 

Tag is justa short keyword which uniquely identifies your post or your site..,.
tags makes it easy for every1 to understand,,..

 

A tag is a keyword.. simple as that

 

Use a text editor (notepad, pspad, etc.) and open the .html of the page you want to use tags on. The ones you need are:
1. The Title tag
<title>page title</title>

2.The Description tag
<meta name="description" content="page description">

3.The Keywords tag
<meta name="keywords" content="a bunch of keywords">

4.The H tag
<Hn>Heading</Hn>

Change the Italics above into words that describe your website. Save. Publish on the server. Happy end!

 

If you're selling electronics then you would tag things like cables, plugs, adapters with the word "accessories"

when a user clicks on this tag word it should bring up all the posts with "accessories" as the tag. It makes content on your website / blog easier to find.. most wordpress / blogpsot blogs have tags to help users filter through posts quicker

 

A tag can simply be a word/words that best describes the service or info you are offering.

 

Thank everybody,now in my opinion, if i want to creat tag,i could not use some words just like "touch screen mp4", it looks like a keyword,right?Or maybe i should use "media player" and it contained all of the players,like mp3 player,mp4 player and mp5 player,right?
I'm the first time to do that,so i need your help.