Tick chart for BTCUSD, showing each change in the ask or bid price. (If the spread is very tight then the lines may overlap, and only the ask line may be visible.)
As well as a plain tick chart, you can use the "Tick speed" mode to add an indicator showing how long it has taken for the last N ticks to happen. The lower the histogram, the faster the market is moving.
The "Timed" mode still shows each change in the ask or bid price, but the X axis of the chart is set to constant units of time. You can use this to view individual ticks while still being able to distinguish between fast and slow periods in the market.
The "Candles" mode draws tick candles. These are candles which form each time that N ticks happen, rather than being time-based.
The BTCUSD pair is the abbreviation of Bitcoin against the US Dollar. Bitcoin is the cryptocurrency that has the biggest nominal market price and the largest market capitalization. It is considered the main Cryptocurrency whie all other digital currencies are treated as Alternative Coins (altcoins). BTC is commonly valued in terms of the world's reserve currency, the US dollar (USD). Volatility has constant presence in the BTCUSD valuations, with prices fluctuations of 5% or 10% of the value within a 24 hour period. BTC is in its infancy compared to the USD with high skepticism amongst traders as the digital currency has limited supply and the regulatory status is yet to be defined. Questions about its security have also been raised. While traditional currency market influences such as central bank decissions or economic news do not affect BTC directly, the USD remains subject to all of these factors and it can affect the pair.