Essentially, back links are inbound links to a web page or site. This means that another website contains a hyperlink directed towards your site. In terms of SEO, the more back links you have pointing toward your website the better, particularly if the back links are coming from a site which deals with the same field as your chosen speciality.
As the number one goal of a website is to achieve traffic, i.e. people actually looking at the site, it follows that you must make the website visible. Generally speaking, to make your website visible, people must be able to find it when they search for keywords directly related to your product, niche, service or whatever else your website represents. Individuals tend to be seeking such information via the big search engines, whose operators have rather complicated algorithms to help them decide whether a certain website is applicable to the searcher's request, or not.
Although they will not divulge exactly how they go about composing these algorithms, the search engine operators do assure us that relevancy, as viewed by others, is most important. If they see that you have a back link or a number of back links from other websites that have some relevancy to yours, this is a plus. In addition, if the site linking to you has a fairly high "page rank", this helps as well. Page rank is Google's proprietary method of allocating a number (zero being lowest and moving up to ten) indicating how important a site is within its particular niche of operations.
There are a number of ways to achieve back links for your site.
As Bill Gates once said, "content is king". Article marketing is known as one of the most solid Internet marketing methods. By writing highly relevant and informative articles and submitting them to high profile article directories you do several things, not the least important of which is to help establish you or your site as an expert in your niche. Within your article, published in the article directory, is a resource box which contains your details - who you are and what you do, and a link back to your site, the all important Back Link.
There are many hundreds of social bookmarking sites, and their primary motive is basically to provide a way of informing people about the existence of content related to any niche or interest in a very manageable format. You can sign up and initiate a process of notifying social bookmarking sites about fresh content, including back links in many cases. You should note at this stage that some webmasters apply a "no follow" tag which can void the effect of a back link, as the tag instructs the search engine spider not to give you points, or what's called "link love".
SOCIAL MEDIA - TWITTER.
Whilst Twitter and other similar sites are becoming increasingly more powerful in marketing terms, you should know that to include links within your "tweets" or in your URL profile box is not a powerful back linking strategy, as these are all allocated the dreaded no follow tag. However, you may find that it is possible to link within a bio box and get some link love this way. Also, if you syndicate, your Twitter feeds are updated via the RSS aggregators, earning you back links.
First of all, you will have to locate blogs or forums that are relevant to your area of expertise. This is fairly simple to accomplish as a straightforward and pertinent search will locate hosts. Once you find these blogs you can sign up and create a profile. Often you will be allowed to create what is called a "signature", and within that signature you incorporate your links. Note, you should check to see if there are any no follow tags, as these will appear occasionally.
Enter into the spirit of the place by interacting with other members and making entries and posting comments that are relevant, useful and educational. As well as a back link being displayed each time you post a comment, you'll also create a potentially profitable bond with other members - and this has the potential to lead to all kinds of new possiblities.
Back link building remains one of the most important SEO strategies to adopt.