Screen　content,　which　is　often　computer-generated,　has　many　characteristics　distinctly　different　from　conventional　camera-captured　natural　scene　content.　Such　characteristic　differences　impose　major　challenges　to　the　corresponding　content　quality　assessment,　which　plays　a　critical　role　to　ensure　and　improve　the　final　user-perceived　quality　of　experience　(QoE)　in　various　screen　content　communication　and　networking　systems.　Quality　assessment　of　such　screen　content　has　attracted　much　attention　recently,　primarily　because　the　screen　content　grows　explosively　due　to　the　prevalence　of　cloud　and　remote　computing　applications　in　recent　years,　and　due　to　the　fact　that　conventional　quality　assessment　methods　can　not　handle　such　content　effectively.　As　the　most　technology-oriented　part　of　QoE　modeling,　image/video　content/media　quality　assessment　has　drawn　wide　attention　from　researchers,　and　a　large　amount　of　work　has　been　carried　out　to　tackle　the　problem　of　screen　content　quality　assessment.　This　article　is　intended　to　provide　a　systematic　and　timely　review　on　this　emerging　research　field,　including　(1)　background　of　natural　scene　vs.　screen　content　quality　assessment;　(2)　characteristics　of　natural　scene　vs.　screen　content;　(3)　overview　of　screen　content　quality　assessment　methodologies　and　measures;　(4)　relevant　benchmarks　and　comprehensive　evaluation　of　the　state-of-the-art;　(5)　discussions　on　generalizations　from　screen　content　quality　assessment　to　QoE　assessment,　and　other　techniques　beyond　QoE　assessment;　and　(6)　unresolved　challenges　and　promising　future　research　directions.　Throughout　this　article,　we　focus　on　the　differences　and　similarities　between　screen　content　and　conventional　natural　scene　content.　We　expect　that　this　review　article　shall　provide　readers　with　an　overview　of　the　background,　history,　recent　progress,　and　future　of　the　emerging　screen　content　quality　assessment　research.