Quick content tip: do not provide undated information on your websites.
If you do not include a date in your content, your text may not be considered relevant and you will look unprofessional.
When a user lands on your website and starts to read an article of yours, he or she needs to know whether the information is up-to-date or not. The relevance of what you write depends on the date. This does not only apply for the articles dealing with the world of internet and technology, where things change rapidly, but all topics.
Upon seeing undated content, the user may well dismiss your article or post and look for other sources of information. I know I certainly would.