One　fundamental　question　about　any　novel　pathogen　is:　how　does　it　transmit?　Answering　this　question　will　help　to　protect　ourselves　from　the　agent,　at　least　until　effective　vaccines　and　antiviral　therapies　can　be　developed,　especially　if　it　is　an　agent　of　moderate　to　high　lethality.　Initially,　at　the　start　of　the　Coronavirus　disease　2019　(COVID-19)　pandemic,　more　emphasis　was　placed　on　handwashing　rather　than　on　droplet　and　aerosol　transmission.　Although　severe　acute　respiratory　syndrome　Coronavirus　2　(SARS-CoV-2)-infected　secretions　such　as　saliva　can　spread　the　virus　to　hands,　it　became　increasing　evident　that　the　virus　mostly　transmitted　through　close　contact　(though　not　necessarily　touching),　whilst　people　were　breathing,　talking,　laughing,　singing,　coughing　and　sneezing　near　one　another.　During　such　respiratory　activities,　droplets　and　aerosols　are　produced　together,　and　the　amount　of　transmission　due　to　these　differentsized　liquid　particles　will　likely　vary　between　individuals　at　different　stages　of　their　infection　and　illness.　This　question　became　even　more　complex　as　it　emerged　that　viral　transmission　can　occur　for　several　days　before　symptom　onset,　and　that　asymptomatic　cases　can　also　shed　just　as　much　virus　and　potentially　transmit　it　just　as　well　as　symptomatic　cases.　This　chapter　summarizes　our　understanding　of　how　SARS-CoV-2　transmits　and　the　infection　control　precautions　to　reduce　this.　©　2023　by　World　Scientific　Publishing　Co.　Pte.　Ltd.