How often are you asked something like:

"How good are you at…"
"Have you used…"
"What is your experience with…"

With regard to technical competency in a given area, what should you say? After giving this some thought, I feel there are three major aspects that come into play:

  1. Academics

    Knowledge & Understanding

    This is a two-part aspect. Knowledge refers to the specifics, while understanding relates to conceptual comprehension. For example, in HTML5 new elements have appeared such as <section> and <article>. Knowledge is awareness of these things and the proper syntax to use them. Understanding is knowing why and when we would use one over the other.

  2. Experience

    Time

    If all you have is the first aspect, then you only have is academics. You would be "all theory, no practice" as the saying goes. How much time you put into actually using the technology is commensurate with your expertise. And I am sure you will agree that the more time you spend on any technology, the more likely through "trial and error" you learn more too.

  3. Context

    How

    How you apply the technology is also a factor. Using HTML5 to create a friend's personal website will (likely) not give me the same challenges as a Fortune 500 company needing a new internet site. The context of the technologies surrounding a technology also comes into play. For example, loading a web page with static data vs. loading a data from a service in the cloud – both end up the same, but the level of skill to complete one or the other is considerably different.  In this aspect the scale of use is also factored.  Creating something to please 10 people is far different from creating something to please 10,000,000 people.

Any of the above aspects deserve much more explanation.  This is just my rough-draft thinking.  Imagine an algorithm that would put these into numerical measurement.  Something like:
TL = (A+E2)C
Technical level equals context multiplied by the sum of academics and experience weighted twice important

If each aspect were given a scale of 1 to 5, what would your technical level be?