Canvas FAQ: ask questions

Hello to all! Often in the comments and in the personal questions arise at the expense of the Javascript Canvas.
Most, even if they have theoretical knowledge, simply do not have enough experience.
I have this experience. Therefore, in this topic I propose to ask questions on the Canvas, to which I will answer the following topic.
If there is no region on Habré, you can drop your questions at shocksilien@gmail.com, I will add it to the topic.
Initially I wanted to throw in q & a, but the quantity and quality of questions in the comments to this topic will positively affect the quality of the next topic, so I count on your support)

ps. Feel free to ask questions that you think are stupid. If they interest you - ask them.
pps. I will ask clarifying questions. For example, "for what purpose?". This does not mean that the question is wrong. This means that, depending on the purpose, there may be different solutions.

Answers