Title tags are probably one of the most important factor that affects the search engine optimization (SEO) of your web page. The content of the web page does matter a whole lot more, but when used appropriately with the title tag it complements the page content and thus increases the relevance of your content in the search engine indexing.
Word separators can defined as any character that is used to separate words or parts of sentences that convey different semantic meaning. The title of a web page can have different parts, including the content header, page category, blog name or brand name each of which can be separated using a character to make the semantic distinction clearer.
Many a times the title tag can be created without the use of any word separators or any special characters in the title. Sometimes the use of these separators are unavoidable, especially when the title contains multiple segments as mentioned above.. There are several characters that can be used as separators such as comma (,) pipe (|), colon (:), ampersand (&), underscore (_) or hyphen (-). In addition to these you can also use any of the other special characters that might be appropriate such $, %, # etc etc.
From a SEO point of view, different search engines and the underlying indexing algorithms deal with these characters differently. But there is one common thing they all strive to achieve: To identify a natural sounding and well crafted title that is meant to appeal to the reader and not just for the search engines. These are normal English (or other language) sentences that accurately describe the content of the webpage.
Minimize the use of word separator
There is definitely no limits on how many of these separators you can use in the titles. But it is the use of too many word separators in a sentence raises red flags about keyword stuffing. Avoid using a large number of them, and minimize the use of separator characters to 2 or 3 at the maximum. It is very unlikely that a natural sounding title will have much more than 2 or 3 of them anyways.
To minimize the use of separators, you can use stop words instead of the word separators to convey the same meaning. This is also often the case when you also want to increase the character count or make the title longer. The stop words also have the advantage that it does make the title more readable.
SEO influence of the word separator
Almost all word separators have equal or similar SEO influence. You should, therefore use them appropriately and as desired. The only character that you should avoid if at all possible is the underscore ( _ ). It is very unlikely that the underscore can be part of a sentence, unless it is very specific to the subject matter itself.
Also, avoid using the underscore character instead or in lieu of the hyphen. Most search engines tend to consider the underscore as a character rather than a separator. This means that the underscored word is considered as a single word while a hyphenated word will be considered as two different words. This increases the potential of the keyword matches by the search algorithm.
Ranking high in the SERP (Search Engine Results Page) is important. And sometimes keyword stuffing the title will allow you to rank higher for a short while. Equally important is the CTR (Click-thru Rate) on the results page. If the title is skewed towards the search engine and not towards the user, then it is highly likely that your page will garner less clicks in spite of being ranked higher. When your CTR is low, it tells the search engines that your web page is not as relevant even as the title suggests and that it needs to get demoted in the results.
When you create the title for your page, imagine how the complete blog title will look in a search engine results page. Does it look natural and prompt the user to click on it?
No matter what characters or word separators you use, use it to increase the readability of the title and not to stuff the title tag with all the different keywords into a single sentence. Playing by the (expected) rules in this case has multiple advantages. As the search engine algorithms get smarter over time in figuring out keyword stuffing and unreadable sentences, your title can be popular for a long time irrespective of the changes in the search technology.