[Mayte]

What does this mean? What are differences?

[jm2hill]

unlocked means that you can use it on any gsm network provider
locked means you can only use it on the gsm network it was bought from

[amazinglygraceless]

Locked means it can only be used to the carrier it is branded to.

Unlocked means it can be used on any GSM carrier network (those
that use SIM cards)

Unlocking is useful if you want to switch carriers but not phone.

If you travel internationally you can buy a SIM card in your
destination and avoid international roaming charges.

And lastly if you decide to sell it you can usually get more for
an unlocked phone. You also increase your pool of potential buyers.

[benzworm]

going along with what jhill3206 said, having it unlocked also increases the resale value

[Mayte]

like you I am on Rogers-so what does that mean"other networks"?

[jm2hill]

at&t
vodafone
if its unlocked any service provider with a sim card