Complex sentence: Shipping portals are web-based communities which allow shippers, consignees and forwarders access to multiple carriers through a single site and concentrate on providing bookings, track and trace, documentation functions, and allow users to communicate with their carriers.
Split into simpler sentences: Shipping portals are web sites which allow shippers, consignees and forwarders access to multiple carriers through a single site. Portals provide bookings, track and trace, and documentation, and allow users to communicate with their carriers.