Share of voice (SOV) is the proportion of all the relevant conversation in your category that is about your brand rather than your competitors. On social it is usually your mentions divided by the total mentions of you plus your named competitors, over a set period, expressed as a percentage.
It matters as a competitive, market-level view that raw follower counts miss. A rising share of voice means you are winning attention in your space; a falling one warns that rivals are out-talking you even if your own numbers look flat. Paired with sentiment, it separates loud from loved.
Measure it with social listening across a consistent set of competitors and terms, and track it as a trend rather than a snapshot. Read it alongside sentiment analysis and share of engagement so you value quality of conversation, not just quantity, and set it as a goal for awareness campaigns.