When we first start off, all our votes are at 100% Power. Which means the WEIGHT of your vote is at the maximum each time you vote. As you get alittle more STEEM POWER and aren't quite a little fish anymore, if you hold your mouse over the UPVOTE (green) button, it gives you a slider. This slider allows you to adjust your voting power from 1% to 100%.

Let's just say you have enough VOTING POWER that each of your votes are worth $1 each time you upvote. Each time you upvote, the slider let's you adjust the power of that $1. So if you adjust your vote to only 5% of power, you are giving that person .05 cents of STEEM. If the article is really good and you want to give it ALL the power you would adjust it to 100% which will give it $1.00.

The only problem with giving 100% voting power to an upvote is that it drains your OVERALL VOTING POWER and you can only give like 9 other FULL POWER votes in a 24 hour period.

Not sure if I explained that clearly. Hope I did.

The upvote slider, looks like this