Importing and exporting vCards
Getting contacts in from wherever they are now, what the import tells you afterwards, and exporting the lot.
vCard (.vcf) is the interchange format for contacts. Every phone, mail client and address
book exports it, which makes it the way in and the way out.
Importing
Import .vcf takes a file, which may contain one card or several hundred.
Afterwards Steerd tells you what happened:
{created}newly imported,{updated}updated.
It matches and updates rather than blindly creating, so importing the same export twice does not give you two of everybody. That matters because the natural way to use this is to re-export from your phone occasionally and re-import.
Cards that could not be imported are reported as a count. A card usually fails because it carries no usable name.
Exporting
Export all gives you a single .vcf of every contact, which is both a backup and the way out
if you ever leave.
There is no partial export. If you want a subset, the phone sync is the better tool, since it gives you the contacts continuously rather than as a file.
Import or sync?
Import is a one-time move: you have contacts somewhere else and you want them here.
Sync is ongoing: your phone and Steerd stay in step, both ways.
Most people import once at the start and sync forever after. Doing both is fine; the import's matching is what stops that producing duplicates.