What is the difference between 'ser' and 'estar'?

'Ser' is used to describe the permanent state of something, aka what something is. These are qualities which aren't going to change any time soon, and are the qualities which define a person or object.
Specifically, we use 'ser' to talk about:physical characteristicsdescriptive qualities (what makes something what it is?) the time/datenationality occupation (job) possession where an event is taking place
e.g. Yo soy Laura. I am Laura.
Soy inglesa. I am English.
Soy rubia. I am blonde.
'Estar', on the other hand, describes a temporary state, aka how something is at that time. This is something which could change easily.
We use 'estar' to talk about: Geographical/physical locationsTemporary conditions such as emotions or a short-term illnessOngoing actions (ending in -ing) e.g.
Estoy en Edimburgo. I am in Edinburgh.
Estoy feliz hoy. I am happy today.
Estoy cantando. I am singing.