advertisement (ad)
Use the full version in the first instance, subsequently the acronym.
add-on
Depends on context. Hyphenate if using as a synonym for plug-in.
always-on
Hyphenated.
Aruba
Must be written as ‘Aruba, a Hewlett Packard Enterprise company’ the first time you use the name. Subsequently, ‘Aruba.’
artifical intelligence
AI Sentence case. In formal copy, ‘artifical intelligence’ in the first instance, subsequent use ‘AI.’ In titles and less formal content, you can use ‘AI’ e.g., ‘AI-driven.’
application app
Use the full version in the first instance, subsequently the acronym.
as a Service
No hyphens. Capitalise the given service and the word ‘Service’, e.g., ‘Software as a Service.’