Microsoft hotfix is a service provided by Microsoft to fix product problems or change the product behavior. To get a hotfix, you may contact your Microsoft contact or get it from web (Hotfix KB, download center, Windows Update, office Update, Service Packs , etc).
A hotfix is available when a bug is identified and fixed. The common process is as following:
A hotfix may take several days to months from the problem being identified to a bug. It depends on the different products and different business impacts.
Not every problem will be fixed. In certain conditions, the product team triage may reject a bug. For example, if the problem has limited impacts to seldom customers, or the changes may cause other potential risks, the bug will be rejected.
As a service, there are different phases for the hotfix, based on the Microsoft Support Lifecycle:
10 years of support (5 years Mainstream Support and 5 years Extended Support) at the supported service pack level for Business and Developer products
5 years Mainstream Support at the supported service pack level for Consumer/Hardware/Multimedia products and Microsoft Dynamics (formerly Microsoft Business Solutions) products
3 years of Mainstream Support for products that are annually released (e.g., Money, Encarta, Picture It!, and Streets & Trips)
In Mainstream Support, you can get a free hotfix. In Extended Support, Extended Hotfix Support Agreements (EHSA) are designed to provide opportunities to extend non-security hotfix requests through the end of the Extended Support Phase. Security hotfixes are available free of charge during this phase.