Now we will look at some of the more complicated rules of using ‘the’.
When it is shared knowledge between the speaker and listener, we use ‘the’. For example, 2 colleagues at work might say ‘The boss is in a meeting’ because they work together, they are both clear that this refers specifically to their boss. When we are referring to something which is unique (there is only one) we also use ‘the’. For example ‘There is a lot we have to discover about the solar system’. Names of rivers, seas, oceans and deserts also take ‘the’, as in The Thames, the Pacific, the Sahara. Certain countries (when they are considered to be groups of places) also use ‘the’. For example: the United Kingdom (England, Scotland, Wales and Northern Ireland), The Caribbean (a collection of islands), the United States (a group of states).