Facebook advertising is more proactive method where your ad is constantly under his glance.
Super Targeting: - You can target people belonging to different segments say age group, interests, types, etc or you can target them as a whole.
Local stronghold: - if you are a small business you can target people only from your local area. This will give you a stronghold on local market.
Analyze Reach: - when you design your ad you get a rough idea about the possible reach of your advertisement. This will help you make a strong business strategy.
Snowball effect: - when someone like or shares your ad it is displayed on the common news feed which is seen by many other users. Hence it sets up a chain reaction or a snowball effect which can propel your business.
In short Facebook adds new concepts of demographics and ads to the already existing qualities like keyword search and locality based marketing.