I suppose that really depends on the person who answers, and what their personal beliefs are.
For me, magick is an energy that is all around us. We do not control it, we can however, ask for a magickal result by undertaking spells, rituals or other practices.
But of course, other people will likely have very different views than me.
Magick is the science and art of causing change to occur in conformity with will. -Aleister Crowley
A good rule of thumb I tend to follow is; If you cannot do it without magick, you cannot do it with magick. What I mean is a lot of magick is used for helping you to do things that are already possible and simply increasing your chances. Like drawing money, love, luck, etc. It still requires work on the mundane. Like a money spell will likely not work if you are not doing anything that you could possibly make a profit from. A love spell is less likely to work if you never leave your house to meet anyone and rarely talk to people.
Other definitions of magick I have come across are those who believe working with spirits is magick and everything else is just wishing really hard. Another is that gods and spirits do not exist and it's all about energy, the vibrations of stones, and mental connections you make to things, etc. So two extreme examples there I have heard. Both of which I highly disagree with but still respect all the same.
Something I like to stray away from a bit is the concept of 'energy,' though it is a very quickly thrown around word.
It can be used to express many things from the energy of effort, such as moving the sofa to a third-floor apartment takes a lot of energy.
There is also the concept of -- what I find to be the best term, in my own opinion, taken from the 15th or 16th Century as both a term and concept -- is virtus. It is spiritual 'energy,' and one which has as of yet been defined by science. Basically, based on the context of how it is used, is very similar in concept to chi, or life energy except that it was not used in that sense.
This post is getting a bit long-winded, but it comes to this point: Be careful on the context of 'energy.' Not all types are interchangeable.
The same can be said for 'vibrations' and 'frequency.' A lot of people seem confused, and use these terms as a universal concept, believing that since sound is a vibration, since radio waves are vibrating electromagnetic fields, that all things vibrating can be affected by magic in ways similar to fiction. Again, just be careful.