The Open University is a proper noun. “Proper” in this sense is like “property” – it means “belonging to someone or something”. A proper noun is the official name of someone or something.

Proper nouns should almost always be capitalised. It would be wrong to write the open university, if you meant the British university based in Milton Keynes.

People’s names are proper nouns. You should write:

• Melanie Rimmer, not melanie rimmer
• Donald Duck, not donald duck
• Jean Piaget, not jean piaget

And so on.

Place names are also proper nouns:

• Milton Keynes, not milton keynes
• City Road, not city road (if you mean the road in Cardiff called City Road)

Business names are also proper nouns:

• The Macintosh Centre, not the macintosh centre
• Taste Buds Café, not taste buds café

There are a few exceptions; for example the feminist bell hooks chose to write her name in lower case to honour her grandmother. The business eBay starts with a lower case letter. But the general rule is always capitalise proper nouns.