Outbound versus inbound change sets
Key Takeaway
Uploading an outbound change set sends it to the target org, but nothing takes effect until someone there deploys it as an inbound change set.
A change set moves customizations from one Salesforce org to another, such as from a sandbox to production. The same change set has a different name depending on which side you are on. You build and upload an outbound change set in the source org, which is the org that sends it. The target org, which is the org that receives it, sees the change set as an inbound change set, and someone there must deploy it.
What a change set can carry
Change sets carry only changes you can make through the Setup menu. They move metadata, not data such as records, so you can't use a change set to upload a list of contact records.