The four major markets to trade include the London Session (3am EST-12pm EST), the New York Session (8am EST to 5pm EST), the Sydney Session (5pm EST to 2am EST), and the Tokyo Session (7pm EST to 4am EST). During summer and winter months from 8am to 12 pm the London and New York session overlap.



The London Session

It is this session that 99% of traders keep their eyes on as London controls essentially the entire European market movements. Roughly 30% of all market transactions take place in the London Session.

The following is important to keep in mind when trading the London Session:

Due to the London Session overlapping with two other major trading sessions, a large portion of Forex transactions are made during this time. This leads to a massive surge in liquidity which can also lead to lower transaction costs as there will be more volume per user at the broker level.
The London Session is known to be specifically volatile for the EUR/USD (EU), as there is a plethora of European news that is released within a couple hours of the opening of this session.
Most Major movements that occur during the London Session also carry over into the New York Session.
The best times to trade the EU & GBP/USD is during the overlap of the London & New York Session.
Price action may slow down and trends start to change as European traders close their trades and take their profits.

The New York Session
This session begins at 8am EST. This is the most traded session amongst all Forex traders, primarily due to influential market news that makes market moves occur during this session. The most commonly traded pair during this session is the USD/JPY or EUR/USD, as well as Gold sometimes.

The following is important to keep in mind when trading the New York Session:

Major news is released in the beginning.
Every major transaction in the world involves the USD, so whenever any major news comes out which affects the USD anything that is directly related to it will move drastically.
The New York Session begins to majorly slow down after 1pm EST.
There is almost little or no movement Friday afternoons as Asian and London traders are done for the weekend.

The Tokyo Session
The Tokyo Session is often referred to as the Asian session because Tokyo is the financial capital of Asia. Japan is the third largest trading center in the world, and the Japanese Yen is the third most traded currency partaking in 16.5% of all forex transactions. Overall about 21% of all transactions take place during this session.

The following is important to keep in mind when trading the Tokyo Session:

The most commonly traded pair is the USD/JPY.
The Bank of Japan (BOJ) has been known to inject massive amounts of government printed money into the markets should they feel their currency is getting too strong. This has caused the markets to move 2000 pips within 20 minutes in the past.
Liquidity can often be very thin, therefore making this session boring because of the lack of activity.
It is more likely to see movement in Asia Pacific pairs like the AUD/USD and NZD/USD opposed to pairs like the GBP/USD.
Most action takes place early in this session due to major economic data that is released. The AUD/USD is known to make large movements during this time.

The Sydney Session
This session is starts and ends the trading week Starting on Sunday at 5pm EST and ending the week at 5pm EST. This session focuses on the volatility of AUD pairs. (ex. AUDUSD, GBPAUD, AUDJPY. Normally this session has a very low volatility compared to the other sessions.