Colds, flu and Covid-19 are caused by different viruses, but can have similar symptoms.
It can be hard to judge which one you may have.
Most people who feel ill with coronavirus will have at least one of the key symptoms:
* a high temperature
* a new, continuous cough
* a loss or change to their sense of smell or taste
So what do you need to know about other things you may catch in the coming months?
Does a fever mean I have coronavirus?
A high temperature is 37.8C or above. A fever like this can happen when the body is fighting off any infection - not just coronavirus.
It is best to use a thermometer to take a measure. But if you don't have one, check if you, or the person you are worried about, feels hot to the touch on the chest or back.
Although fever is a key coronavirus symptom, it could be flu or a different infection.
A high temperature is unlikely with a cold.
If you have a fever, arrange a coronavirus test - you can use the NHS 111 coronavirus service online.
What about a cough?
If you have a cold or flu you may well have a cough, along with other symptoms.
Flu usually comes on suddenly and sufferers will often experience muscle aches, chills, headaches, tiredness, a sore throat and a runny or stuffed nose, along with the cough. It feels worse than a heavy cold.
Colds tend to develop more gradually and are less severe, although they do still make you feel unwell. Along with a cough, there may be sneezing and a sore throat and runny nose. Fever, chills, muscle aches and headaches are rare.
A coronavirus cough means coughing a lot for more than an hour, or three or more coughing fits or "episodes" in 24 hours.
If you usually have a cough because of a long-standing medical condition like COPD, it may be worse than usual.
You should get tested for coronavirus if you develop a new, continuous cough.
What do loss or change to smell or taste mean?
These are key symptoms of coronavirus and mean you should get a test.
It could still be that you have a simple cold. But you need to check, even if you don't feel unwell, to avoid the risk of spreading the virus.
Does sneezing mean I've got coronavirus?
Sneezing is not a symptom of coronavirus, and unless you also have a fever, cough or loss of smell and taste, you do not need a test.
Sneeze droplets can spread infections though, so catch them in a tissue, put it in the bin and then wash your hands.
Remember Hands. Face. Space to help stop the spread of coronavirus and other illnesses:
* Wash your hands regularly
* Use a face covering when social distancing is not possible
* Try to keep your distance from those not in your household
More people in England are being offered a free flu jab this year too in the run-up to winter.
How about a runny or blocked nose?
As we head into winter and with children back to school and more workplaces open, lots of people will be getting colds.
A runny nose is not a reason to get tested for coronavirus, says NHS Scotland.
Data from an app that has been monitoring Covid-19 symptoms, reported by UK users, suggests children present less often with respiratory symptoms and are more likely to be suffering from fever, headaches, fatigue and skin rashes.
What if I am very unwell?
People with coronavirus have a wide range of symptoms, ranging from mild to severe, although some will have none at all, but can still be infectious.
Symptoms may appear up to two weeks after exposure to coronavirus, but usually around day five.
Feeling breathless can be a sign of a more serious coronavirus infection.
If you are having trouble breathing, contact your doctor online or over the phone, or the NHS 111 online coronavirus service.
If you are very worried about sudden shortness of breath ring 999.
And the NHS advises:
* Call 111 if you're worried about a baby or child under five
* If your child seems very unwell, is getting worse or you think there's something seriously wrong, call 999
* Do not delay getting help if you're worried. Trust your instincts