Ascending Channel
An upward moving channel formed with two parallel, upward sloping trendlines. The upper trendline connects a stock's highs over a period, with each subsequent high price higher than the previous. Conversely, the lower trendline connects the stock's lows, with each subsequent low price higher than the previous. 
Investopedia Commentary
As a general rule of thumb, the failure of any move within an established price channel to reach one side of the channel usually indicates that the trend is shifting and increases the likelihood that the other side of the channel will be broken. Thus, the clearing of the upper trendline could indicate an accelerating (upward) trend and the clearing of the lower trendline could indicate a decelerating (upward) trend.
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See also: Channel, Descending Channel, Horizontal Channel, Profit-Taking, Range-Bound Trading, Resistance, Support, Trendline