'Awkward silence' is what we call a longer than usual gap in the flow of speech between two or more people. It's perceived to be uncomfortable, odd, undesirable. Any of the participants in the conversation can be the one to blame, responsibility shifts at the same speed as speaking turns.
If it's your turn to speak but you don't do so straight away, you will get some attention as expectation builds up. A short pause can be tolerated, but as it continues to elongate, the reaction from your listener will gradually move away from easiness and closer to confusion.
This is not inherently bad, we need a degree of continuity in our speech to let the other or others know that we are engaged, that we are listening and doing our best to contribute to the common goal of a conversation (which is an effective transfer of information or opinions between people).
However, sometimes a generous amount of silence is needed to progress certain kinds of conversations, or even to suit certain speakers. The thoughts we're looking for in each specific scenario don't always come instantly, there are times when we need to stop and consider, reflect, clarify, deconstruct ideas and build them back together, and even though all of this can happen in a matter of seconds, sometimes a few seconds feel like too long.
We could attribute this to our current attention economy, or to a generalised lack of patience due to us being now used to technology moving so fast. In any case, thinking can't be outsourced, so it's up to us to agree on the best way to make space for muted reflection in the middle of an exchange of ideas.
I would advocate for longer silences being normalised, to increase the average acceptable silence length by a second or two, so that when that margin is needed for reflection it can be used without it being accompanied by any level of social stigma.
At the end of the day, an 'awkward silence' is no more than a construct, a moment of silence only becomes awkward when most of us agree that it has, so if we all employed slightly longer silences in conversation, then the definition of 'awkwardness' in this context would adapt. Or in other words, if we're all awkward then no one is.
