There exist three kinds of famous charts.

Line Chart: The line chart is a graphical depiction of the exchange rate history of a currency pair over time. The line is constructed by connecting daily closing prices.

Bar Chart: The bar chart is a depiction of the price performance of a currency pair, made up of vertical bars at set intraday time intervals (e.g. every 30 minutes). Each bar has 4 'hooks', representing the opening, closing, high and low (OCHL) exchange rates for the time interval.

One use of technical analysis is to derive "support" and "resistance" levels. The underlying idea is that the market will tend to trade above its support levels and below its resistance levels. A support level indicates a specific price level that the currency will have difficulties crossing below. If the price repeatedly fails to move below this particular point, a straight line pattern will appear.

Resistance levels on the other hand, indicates a specific price level that the currency will have difficulties crossing above. Recurring failure for the price to move above this point will produce a straight line pattern.

If a support or resistance level is broken, the market is then expected to follow through in that direction. These levels are determined through analysis of the chart and by assessment of where the market has encountered unbroken support or resistance in the past.

Moving averages provide another tool for tracking price trends. A moving average is in its simplest form an average of prices that rolls over time. A 10- day moving average is calculated by adding the last 10 days' closing prices and then dividing them by 10. On the following day, the oldest price is dropped, and the new day's closing price is added instead; now these 10 prices are divided by 10. In this way, the average "moves" each day.

Moving averages provide a more mechanical approach to entering or exiting the market. To help identify entry and exit points, moving averages are frequently superimposed onto bar charts. When the market closes above the moving average, it is generally interpreted as a buy signal. It is in the same way considered a sell signal when the market closes below the moving average. Some traders prefer to see the moving average line actually change direction before accepting it as a buy or sell signal.

The sensitivity of a moving average line and the number of buy and sell signals it produces is directly correlated with the chosen time period for the moving average. A 5-day moving average will be more sensitive and will prompt more buy and sell signals than a 20-day moving average. If the average is too sensitive, traders may find themselves jumping in and out of the market too often. On the other hand, if the moving average is not sensitive enough, traders risk missing opportunities by identifying buy and sell signals too late.

In general, moving averages have their value and if used properly, they can be useful tools for the technical trader.

A trend line helps identify the trend as well as potential areas of support and resistance.  A trend line is a straight line that connects at least two important peaks or troughs in the price action of an underlying tradable. No other price action must break the trend line between the two points. In this way a trend line marks a support or a resistance area where the price has turned (peaks and valleys) and has not been violated. The longer a trend line the more valid it is, especially if price has touched the line several times without penetration. 

The penetration of a long term trend line may be an indication that a reversal of the trend is about to occur. However, there is no guarantee that this will happen. As with all indicators of a price trend reversal, there is no proof method that predetermines where future prices will go.

When a market retests a former low after a considerable rally, it will often find support at this former low point. If this support is sustained, a "double bottom" formation is created, which might signal a future move to significantly higher levels. A similar formation consists of three tests of the same level hereby forming a "triple bottom" formation. Conversely, when a market finds resistance two or three times at a given level over a longer period of time, this creates a double or a triple top, which may imply a future move to significantly lower levels.

A double or a triple bottom formation also provides a good level for a technical sell-stop order. Such a sell-stop order would normally be placed just below the prior lows. Likewise does a double or a triple top formation provide a good level for a technical buy-stop order just above the prior highs.

When a market is moving swiftly in a given direction, it may sometimes pull back as market participants take their profits. This phenomenon is known as retracements and will usually create good opportunities to re-enter the market at attractive levels before the move resumes.

Retracements are often of similar size, and 50% and 38.1% retracements in particular (Fibonaccio ratios) enjoy considerable attention among technical traders.