SEM: SEM is all possible optimization activities on a web site in order to increase the visibility of it on a website.
SEO: Search Engine Optimisation. We are talking about on-page optimization and off-page site. On-page is what is inside the site (code optimization of the website structure or menus improvements weight images, etc...). Off-page optimization is the outside of your website (search for links from other sites to yours).
SEA: Search Engine Advertising. This is advertising via search engines. The links you see on Google and Bing at the top or on the side, those are them. It is also banners through affiliations found on some sites. In short everything that is buying advertising space on the Internet.
SMO: Social Media Optimization for. We are talking about the use of social media such as facebook, twitter, RSS feeds, linkedin, etc... to promote a site. More links from these social networks are extremely important for Google and Bing to index your site.
The SEM can work internet marketing in general. It thus seeks all means to increase the number of contacted a potential customer with our site, and all this via search engines.
SEO is the SEO of our website: The big advantage of SEO is to build on our long-term visibility on the internet. It may even afford to spend a little less time, because if during a period the work was done well, it should not note significant changes in the results of Google. The downside is that is not all this in 15 days, it is sometimes long and well positioned on competitive requests. Another drawback ... is the work of a sufficiently long time in advance: the inertia of these actions is most ... and finally, it is not enough action in one shot to do this. It must still spend a little time.
The SEA is buying space and is perfect for quick visibility on the internet. You can not do better in terms of speed and it is also on the simple principle that is built the business model of search engines. Competition words defines the budget that must be allocated. So be careful measurement of costs involved. Another black spot, the SEA has very little impact (if at all) on SEO and capital invested, and if it does not provide sales: the budget is lost in limbo servers .
The Social Media Optimization with social networks rests to increase the visibility of a website. Some people even manage to sell the truth without resorting to a website. I have a friend who sells shoes through social networks and business is booming. This is however not the case for any business!
As I was saying, social networks are supported and can really have interaction with users. The big concern is that it must be done well as a viral marketing campaign can quickly get a negative effect on the image of the brand. Although this is often temporary negative buzz is always annoying.
Everything is linked to the final: The SEA at first, then the sequence of SEO and SMO is intimately linked especially with the new Google algorithm.