Belly gets hard but no cramps or pain. Is this a contraction?

Soo I’ve noticed my belly gets hard and sometimes when I’m working I can feel it get hard. I don’t have any cramps or pain when it gets hard but I was wondering if this is a contraction or what? I’ve read about Braxton Hicks contractions but it always says something about cramps. Is this normal?

Also is cramping bad during the third trimester?