"Chat" or "Messaging" is used to describe conversations that are held keyboard to keyboard.

These include :

• - apple - "messages"
• - facebook - "messenger"
• - skype - "message blob"
• - linkedIn
• - hangouts
• - google+ / google talk
• - whatsapp
• - Yahoo instant messenger

These are found on both the
Iphone and Mac computer.

These are free as long as you dont use the phone number as a destination.

"Video Messaging"

These are bandwidth hogs, thus
please be sure you have a wifi connection when using them.

These include :

• - apple - "facetime"
• - facebook - "live / group"
• - skype - "video / screen share"
• - hangouts
• - google+
• - whatsapp

This is nearly always free, as long
as the settings / system preferences
are configured to use wifi only.

"Text Messaging" or "SMS" is used to describe Messaging through the phone company.

Most of the "chat" or "messaging"
apps, above, support this.
Simply select a phone number
as the destination.

This is rarely free.