Is progress speeding up? We have ventured into new parts of space, tested the limits of AI and cured the incurable. What comes next?
Review of the year: health and science
Keys to a better world?: This year scientists found a new anti-HIV tool, a baby planet, a test for Alzheimer's and made the fastest chip ever. But will they stand the test of time? Glossary
AIDS - Acute Immune Deficiency Syndrome. It interferes with the immune system, leaving sufferers more vulnerable to common diseases. Around the world, almost 40 million people are believed to be living with the disease.
HIV - A virus that damages your immune system.
Microchip - A very small piece of material containing electric circuits that hold lots of information.
Dementia - A syndrome associated with memory loss and other declining brain functions.
Alzheimer's disease - A progressive disease that causes brain damage over time. It is a common cause of dementia.
Symptoms - Covid-19 causes coughing, a high-temperature, and shortness of breath.