Reg Partition and Replica?

Hi,

I have a doubt regarding to Partition and replica. What is the difference between them?
I created a topic "test1" with 5 partition and 3 replicas. I am sending a message to the topic "test1". I see that different partitions are present in the different Kafka brokers.
Some questions on this topic

1. Will that message be sent to all the partitions?

2. When it will be replicated to all the partitions?

3. When it will be replicated to all the replicas?

Thanks
Bala