Securities in the market can be analyzed on technical levels or fundamental ones, and it is generally best to take both into account, despite the fact that some theories dispute the merits of technical analysis.
Some might say that fundamental analysis is all that you need to make wise investment decisions, and to some extent that is actually correct: at a minimal level, if all you had were fundamentals, you could make wise investment decisions. That does not mean, however, that all technical analysis is superfluous.
Securities are their own creature, to be technical about it: they are not the same thing as the companies that underlie them, and a system of analysis for monitoring their behavior is entirely necessary and natural.
The Efficient Market Hypothesis and Modern Portfolio Theory are theoretical archetypes, in a way, against which more specific, nuanced, and natural theories and phenomena can be observed because without that white screen behind them, the projected images of the market activity are more easily lost in the dark.
A lot of technical analysis has to do with finding trends. If you were to say that there are no such thing as trends, many people would pipe up and inform you that you are mistaken.
Moving averages are a big part of this analysis, and does not take a rocket scientist to see that there is a high probability the trading sessions will line up around the water cooler that is the moving average; it’s the meeting place amid the hubbub of the shorter anomalies.
A technical analyst merely tries to predict when the shorter-term trend is going to wander back to the water cooler.