Backlinks,simply put, are links on an external website page that points to another website page. So, if say, you have a A/C business and one of your suppliers such as Carrier has a page which lists all their authorized dealers and one are one of them. Then a visitor on the Carrier webpage can click on that link that leads them to your webpage. This is a backlink. Building quality backlinks is an “off-page” strategy that Orlando SEO agencies use to improve search rankings
For the referring web page the link is an outbound link and for you it is an inbound link.
For any website backlinks from authoritative website are good. Small businesses with lowish competition, from my experience, do not need a lot of backlinks. Only a few is enough to help them in their search position.
If you are in a high competition market such as attorneys or insurance then you will need a plenty of backlinks to edge out your competitors.
Generally backlinks for .gov sites are the holy grail as they are seen to have a high authority factor.
Getting backlinks is time consuming. Small businesses in a local market should stick to getting links from local sites or websites in their field. I would advise going for links in your local online newspaper, Chamber of Commerce, Better Business Bureau or supplier links.
It is always better to get a few good links then a lot of bad ones. Stay away from companies that offer 100 backlinks for $10. These will be worthless at best and will most likely hurt you in the long run.