According to Alexa, the lower the number on the toolbar the better. Alexa measures this by counting how many other people with the toolbar visit your site. So, if, you get a lot of hits from other people with the Alexa toolbar installed, your number is better.
The stats are used by companies looking to place advertisements on blogsites, which is why the lower the better.
It is very useful if you are looking for PR.
Hi Harriet, I have the Alexa toolbar and I already visit your blog everyday from Entrecard. I have your blog in my favorites and always drop on favorites first. So if you visit mine also, we each get drops and alexa help. Connie, I just visited your blog and liked it. I'll try to remember to visit it regularly.