Where people see your product 7 times are more likely to buy, more people see your brand more like to convert to buy. On an average 5 out of 100 people are likely to buy who come to your website, realistically one of hundred are likely to buy, rest don't.
Re-targeting or Re-marketing are interchangeable words
When some one lands to your website you record him and when he browse websites you show Ad of your company. In other-words you are following him around and keep tracking what kind of websites he is looking at and which product - You show your product before him what exactly he is looking for. What you do is to try to get him come back to your website to buy.