Gmail account has all these while use for emailing purposes. However, with more Google apps and features added over the years, you can do much more with gmail account nowadays as shown below:
For both Android and iphone users
Send/receive email
Backup and sync photos
Use Google drive app files backup and File Management
Use gmail to login to Google Drive account, create Google doc,Google Sheet, Google slides etc
For Android phone users
Backup and sync phone contacts
Backup and restore WhatsApp
etc