What part of speech is “yeah”

'yeah' can serve as an interjection and refer to excitement or agreement about something. For example, one can say 'Yeah, I just got a promotion!' to express their enthusiasm. It can also be used to express agreement, as in 'Yeah, that's a great idea for a plan.' Furthermore, it can be used to refer to something that has been discussed or proposed, such as 'The plan is a go, yeah?'

1. 'Yeah, I'll go to the store and get what we need.'

2. 'Wow! Yeah!'

3. 'What do you think? Yeah?'

when 'yeah' is used as an interjection, it is often followed by an exclamation mark or question mark. It is also often used informally, so it is best to refer to other forms of agreement or endorsement in more formal contexts.