Regional service. VPC = virtual network inside AWS.
Private and isolated by default.

Default VPC

max 1 per region. can be deleted and recreated. 1 per region created automatically.
gets 1 default cidr (172.31.0.0/16)
cidr split into subnets for different azs. (/20 subnets) Subnets assign public IPv4 address.
InternetGW , SG and NACL. Security features SG and NACL.

Custom VPCs

created manually. more flexible. can have multiple cidrs.

references: