Citation Flow is a trademark of Majestic. Citation Flow is a score between 0-100 which helps to measure the link equity or "power" the website or link carries. Citation flow is used in conjunction with "Trust Flow". Together the Citation Flow and Trust Flow form the Majestic Flow Metrics algorithm.
Citation Flow represents an evolutionary leap from our old metric - ACRank - and predicts how influential a URL might be based on how many sites link to it. Links are now not all created with equal weight - and because a strong link will have a relatively stronger influence on URLs, Citation Flow is based on stronger, iterative mathematical logic than the old metric of ACRank.