The default Access Tier used by Blobs is configured at the Storage Account Level
The Archive Tier can only be configured at the Blob Level

Hot

Optimized for storing data that is accessed frequently
High storage cost but lowest access cost

Cold

Optimized for data that has infrequent access and at least stored for 30 days
Useful for data that is older but require immediate access
Lower storage cost and higher access cost

Archive

Optimized for data that is rarely accessed and stored for at least 180 days
If data is deleted before 180 days we need to pay an early deletion charge
Lowest storage cost but highest access cost
Used for storing backups and audit/ compliance related data

This is because the data is stored offline and needs to be rehydrated to be used
The data from archive can also be accessed by copying it into another access tier

Dehydration Priority
Standard Priority: Can take anywhere from few minutes to a few hours
High Priority: Need to pay extra but most objects should be rehydrated in a hour