If I want to get an idea from my head into your head, then I need to communicate.
In a trivial sense that means that I need, at the very least, to talk/write in a commonly understood language. I then need to select words from that language and string them in to sequences whilst following rules of grammer i.e. in English that the word sequence generally follows subject verb object.
Before we go any further, I admit it! I am not particularly good at English grammer.
In a slightly more technical sense, I must select a set of sequenced symbols (typically words) where I have a high belief that the meaning that I associate with those symbols is the same as the meaning that you associate with those symbols.
The word “bonnet” is associated in English (UK) with the cover over the front part of a car (typically over the engine). However the use of the word (symbol) “bonnet” in a conversation with someone who has learnt English (USA) will cause some confusion (misunderstanding), which is a failure in communications. (In American English a car’s “bonnet” is called a “hood”).
Before we can communicate effectively we must agree on the meanings to be associated with the symbols we use. This is particularly important for words which have a context dependant meaning. We will meet some of them later (e.g. service and product).
My 33 years of professional association with telecommunications has included many discussions with colleagues which have pivoted on a mutual misunderstanding. To avoid that happening here I will define (hopefully clearly) my understanding of key words.
Please note that these definitions provide a framework. The definitions are picked for their exclusion properties as much as their inclusion properties.