Linking words

I stand in the middle of contrast and surprise.
I’m short and simple — a tiny disguise.
You think it's yes, then I say no —
What’s my name?

But

I often start a sentence with twist and change,
Two ideas I gently rearrange.
I walk in first, yet I let both stay —
Who am I to balance what you say?"

Although

I’m polite and formal, yet full of surprise,
I hide between thoughts in a clever disguise.
With a comma or two, I often appear —
When contrast is near, I’m always here."

However

I lead to results, I answer the 'why',
If you miss the cause, I help you try.
Something happened — what came next?
Use me to connect the text

So

I give you reasons, I explain it well,
Without me, stories are hard to tell.
If you're confused and don’t know the cause,
Just say my name — and take a pause.

Because