There are several networking resources available on Azure
Virtual Networks
Emulates a physical network, used by virtual machines and other services. It’s just software configuration actual networking is done using Microsoft Global Network.
VPN Gateway
Connects two networks through a tunnel as if they were on the same network, uses a Network Gateway
ExpressRoute
High speed private connection to provided by Azure.
VNet Peering
DDos Protection
Basic level of DDos protection by Microsoft.
Azure Firewall
Protects the network by filtering incoming and outgoing traffic depending upon certain rules.
Network Security Groups
Basic type of firewall, also known as Access Control List, has a static list of IPs to allow or deny.
Private Link
Load Balancers
Distributes traffic evenly among multiple server for optimatl response times.
Application Gateway
A higher level of load balancer with an optional firewall.
Content Delivery Network
Stores common static files on the edge, closer to the users for improved performance.
Azure Front Door Service
Combines a load balancer, a CDN and a firewall.
Network Watcher
ExpressRoute Monitor
Azure Monitor