Why do people check there cervix?

Kath • Mother of #1 Jay-Levi my rainbow🌈 💙my baby girl Emily-Jane born sleeping😞💔currently pregnant with #2 😍❤️

I don't know how to or why people do it I'm just a little intrigued as to why and surely pregnant people shouldn't be doing it? It just doesn't sound safe to me I don't know 🤷‍♀️