is computer a common noun or proper noun

A computer is a common noun.

Common nouns are things that are just as the name suggests, common. An easy way to remember the difference are proper nouns are nouns you capitalize. States and people's names are two examples of proper nouns. Common noun examples include apple, monkey, and cell phone.

"The black snake" the speaker feels sympathy for the snake once it is killed.
" A Narrow Fellow in the Grass" the speaker feels anxious about the snake.