Apps that could help people overcome their worst fears have been developed for smartphones.
One app claims to help people who are scared of spiders, using a technique called systematic desensitisation.
Users have to play video games that feature cartoon spiders which look cute and harmless.
As the game progresses, the spiders start to look more realistic. Eventually players have to help an injured tarantula.
The game was developed by two mental health experts.
However some experts have warned that apps should not be seen as a replacement for seeing a doctor.
About 10% of people have a phobia. We can be afraid of just about anything.
Arachnophobia - fear of spiders
Claustrophobia - fear of being trapped in a small space
Turophobia - fear of cheese
Coulrophobia - fear of clowns
Omphalophobia - fear of belly buttons
Triskaidekaphobia - fear of the number thirteen
Paraskevidekatriaphobia - fear of Why is fear of Friday 13th unlucky?
Globophobia - fear of balloons