Every Web site should reflect a single proposal (Unique Selling Proposition), be it your business, your passion or your digital identity. In these times, where many of us carry out two or three activities together, the best thing could be to open two or three web sites, each one dedicated to one of the activities we deal with.
Be found on the Web
The primary purpose for which a web site is made is to be found on the Web. If you make a Web site but your Web site is not seen from anyone, the work is obviously useless. But how is found a Web site on the Web? Without going into technical details, we must be able to be present in the best possible way in the huge databases of search engines. It is by search engine (Google, Bing, Yahoo etc.) that we all do most of our researches. If I look for "Malaga restaurant" with Google, I basically query the database behind the Google search window.
A big catalog
Search engine databases are constantly updated through continuous scan of the network to find all news, new web sites and updates. When you catalog a book in your archive, you can choose different criteria for cataloging, and most likely these criteria will be organized on a hierarchical basis. For example, a book on Carlo Magno probably would be catalogated at first as a history book, then as a medieval story, then as biographies. So the cataloging hierarchy is
History → Medieval History → Biographies.
You could also catalog it differently, that is, with this hierarchy:
Biographies → Historical figures → Middle Ages.
The difference is important because in the first case, when you go to look for the book on Carlo Magno in your archive, you could start the research from History and then get to the biographies. In this way the biographies, for example, of the football players would immediately be excluded from the research.
In the second case instead you could start the research from Biographies and it is clear that you should look for the book about Carlo Magno among all the biographies that you have cataloged, including footballers.
Search engines databases are immense. A search engine must be able to give you a quick result as close as possible to what you are looking for. If you publish a web site that talks about cooking and together you talk about jurisprudence, the database does not know how to catalog your web site. In this case search engine behaves by cataloging the web site at a higher level in the hierarchy. Not "jurisprudence", not "cooking" but, for example "general culture". Of course, in "General Culture" your web site would be placed in a much larger number of web sites than the catalog related only to "kitchen" or only "jurisprudence".
Present yourself uniquely
The best way to be correctly cataloged by the search engine is to present you in a unique, clear on what you really want to talk about. If you are a doctor your web site could be cataloged in medicine, but if you are specialized in surgery it is better to build your web site clearly dedicated to surgery. If then your specialty is "hand surgery" it would still be better if the search engine could catalog your web site uniquely with the key "hand surgery".
Knowing how the search engine works is really important to emerge among the millions of web sites populating web. The concept that I want to explain you is about "Keywords". When you search on Google, you enter some "key" words in the search box. Search engine returns you a list of resources that are as pertinent as possible to the keys you've entered.
Let's return to the example of the book about Carlo Magno. If you had to look for the book on Google you could insert: "book Carlo Magno". In practice you insert three "keys" that you think uniquely identify the object you are looking for. In the first pages returned by Google you would get the list of books on Carlo Magno that are present in the Google database.
If you insert only "Carlo Magno" instead, Google would give you a bunch of more results. Among these results, perhaps starting from page 30, you would also find the books on Carlo Magno. If you then insert only the key "Carlo", the results would be much more inaccurate and misleading. What I want to point out to you is that the more detailed the keys you enter in the search box, the more relevant the search engine's answer is.
Web sites and keywords
Accuracy of the results returned by the search engine depends in part on the technique of cataloging the database behind the engine, but it depends first of all on the information that the publishers of the online resource (that is, who creates the site), provides to the search engine. In practice it depends on the "keywords" related to the resource.
If you publish a web site of rental apartments in Nerja, Spain, the best choice is to make sure that the search keys related to the web site are precisely "apartment" "rent" "Nerja" "Spain". If the web site was dedicated only to the city of Nerja, your site would not be listed among the sites dedicated to rented apartments in Nerja and it would be more difficult for you to emerge among all the resources dedicated to Nerja. If you then try to tell about all of Spain, probably your apartment would have much more difficulty to emerge in the results.
It is therefore essential to build clear projects with a precise definition of what you want to publish. Of course there are situations where you can not be precise in defining your web site. For news organization or generalist multi-topic blogs is more difficult to identify itself clearly, but in these cases every single page must be published with a clear identification.
An intelligent engine
One last thing to finish: search engines are becoming more evolved and "smart", so it happens that the informations you do not provide when you publish your web site, search engine take them directly by reading your content. So if you call your web site "Spain" (that is, if you focused on the search key "Spain") and then you tell only about apartments for rent in Nerja, search engine would catalog your web site under "apartments in Nerja" , perhaps in a slightly less privileged position compared to more coherent web sites. And if you then want to publish something about Madrid, this content would never be taken too seriously by the search engine!