Azure Terminology

IaaS – infrastructure as a service
https://azure.microsoft.com/en-us/overview/what-is-iaas/
PaaS - platform as a service
https://azure.microsoft.com/en-us/overview/what-is-paas/
SaaS stands for software as a service
https://azure.microsoft.com/en-us/overview/what-is-saas/

IaaS is comprised of highly automated and scalable compute resources, complemented by cloud storage and network capability which can be self-provisioned, metered, and available on-demand.

PaaS functions at a lower level than SaaS, typically providing a platform on which software can be developed and deployed. PaaS providers abstract much of the work of dealing with servers and give clients an environment in which the operating system and server software, as well as the underlying server hardware and network infrastructure are taken care of, leaving users free to focus on the business side of scalability, and the application development of their product or service.

SaaS has a main difference of being hosted by a vendor where iPaaS is cloud-based. Applications that are on-premise hosted can be integrated and allow for free flow of data. The application or service is made available to customers over a network, usually the internet.

aPaaS - application platform as a service

https://azure.microsoft.com/en-us/resources/gartner-apaas-magic-quadrant/en-us/

iPaaS - integration platform as a service

https://azure.microsoft.com/en-us/blog/announcing-azure-logic-apps-general-availability/

aPaaS allows for rapid application development and delivery. This form has high productivity and high control. The coding process for platforms as a service can slow down delivery, but aPaaS brings automation for the application lifecycle. aPaaS offers a faster way to build apps
iPaaS is a cloud-based integration solution, unlike SaaS which is hosted by a vendor on-premise. It iPaaS allows applications that reside on the cloud or on-premise to integrate and have data flow freely between them. It does not need any download, it is simply deployed. This is the most balanced offering because it can bring differently hosted software solutions or applications together.

Reference

Cloud Service Models (IaaS, SaaS, PaaS)https://www.cmswire.com/cms/information-management/cloud-service-models-iaas-saas-paas-how-microsoft-office-365-azure-fit-in-021672.php

Azure Glossary
https://docs.microsoft.com/en-us/azure/azure-glossary-cloud-terminology

Cloud computing terms
https://azure.microsoft.com/en-us/overview/cloud-computing-dictionary/
Compare AWS and Azure
https://www.cloudyn.com/blog/azure-terminology-for-aws-speakers/
Windows Azure Platform Glossary for IT Pros
https://blogs.technet.microsoft.com/yungchou/2011/04/21/windows-azure-platform-glossary-for-it-pros/
https://ryvit.com/the-difference-between-ipaas-apaas-and-saas/
https://www.computenext.com/blog/when-to-use-saas-paas-and-iaas/
https://msdn.microsoft.com/en-us/magazine/ee309870.aspx

Azure Maintenance

Use TRIM with unmanaged standard disks
https://docs.microsoft.com/en-us/azure/storage/storage-about-disks-and-vhds-windows