What type of system converts between plaintext and ciphertext?

Cryptographic system converts between plaintext and ciphertext. Cryptography is the process of making and using codes to secure transmission of information.
The cryptographic system involves encryption (the process of converting original message into a form unreadable by unauthorized individuals) and decryption (the process of converting the cipher text message back into plaintext so that it can be readily understood.)

This is very true

cyberstalking on the internet means to harass or stalk someone, a group, or an organization. this may include defamation, slander, and false accusations. in many jurisdictions, cyberstalking is a criminal offense. 

on the other hand, cyberbullying focuses more on intimidating, threatening or harassing someone. harmful bullying include posting threats, rumors, and sexual remarks.