Dyslexia affects the way you recognise the sounds that groups of letters make. It can make it hard to read and write amongst other things.
It doesn't affect intelligence and it's not a disease or illness - it's a condition you're born with.
Some people learn special techniques to help them cope with dyslexia whilst others need special support.
What's it like for someone who has dyslexia?
Not everybody with dyslexia has the same experience.
Some people suffer with reading and writing, others with maths. A lot of people also struggle to remember things.
It can make simple things like going to the shops difficult. You might not remember what you wanted to buy and can't read your own shopping list.
Some children say words move about the page when they try and read. It makes school work difficult to complete and some children fall behind without special help.
Unfortunately some kids get bullied because of their dyslexia.
How do people with dyslexia cope?
There are lots of different ways children manage their dyslexia.
Some children who struggle to remember things use a voice recorder to set reminders. CBBC star Dom Wood says he learns his scripts by repeating them over and over!
Children who have trouble reading sometimes put coloured overlays over text which can help them read.
Others benefit from special learning techniques or personal tutoring - but not all schools provide it.
How many people have dyslexia?
Dyslexia is very common - about 1 in every 10 people in the UK has it.
What causes it?
Dyslexia is caused by differences in the language areas of the brain and the connections between them.
It often runs in families and can affect people of any age from any country.
Is it curable?
Dyslexia can't be cured and people who are born with dyslexia have it all their lives.
Luckily it can usually be managed and people with dyslexia can go on to be hugely successful - like business tycoon Sir Richard Branson!
Want to know more?
Why don't you watch My Dyslexic Mind a special Newsround film about dyslexia. Or you could play Try Being Me, an interactive experience designed to give you a better idea of what it's like living with dyslexia.