We're going to give a glance on a very basic trading strategy. You can read this Investopedia article if you are interested.

These are the prices in 2017 of a company in Spain Stock Market.

For each price, we compute the average price for the previous 12 sessions (fast average) and 26 sessions (slow average):

The strategy is: when the fast average curve crosses above the slow average curve it's a buy signal. Prices will increase in the following days.

Do you agree after playing for a while with next slide?

Disclaimer: please do not put your money on stocks using only this extremely simple strategy. Consult a professional advisor.