1. Inside means within something else.

Pattern: verb + noun + inside + noun
There are some little toy animals inside the box.
She put the money inside the envelope.

2. Inside (adverb) means indoors, within a building.
It started to rain, so we went inside.

Fact
'Three dog night' (attributed to Australian Aborigines) came about because on especially cold nights these nomadic people needed three dogs to keep from freezing.      .. More >>