Freestyle stroke is the easiest stroke for beginners to learn until they feel comfortable in water. For competitive swimmers officially freestyle swimming means they can swim any stroke, but, front crawl being the fastest freestyle swimming technique most swimmers choose it.

Breathing

Breathing is the most difficult part of freestyle (front crawl) stroke. Since the face is in the water, so to breathe you must take your head to the side when your arm comes out of the water. Avoid inhaling at other times while swimming. Inhale after 2 or 3 strokes.

Posture

The body should be as close to the water surface as possible while the trunk should maintain the shoulder-hip connection. Imagine a line running down the centre of your body from the chin to the chest on which your whole body should pivot. Your eyes should focus on the bottom of the pool when you are not breathing. Keep your forearms loose, so they can swing forward easily. Your legs should be straight (not rigid) with your toes pointed out.

Movement

The freestyle swimming technique requires a simple flutter kick and an alternating arm windmill motion, in prone position.

The arm stroke:

Keep your hands flat, thumb separated from your index finger and pull the right arm under the water. Bending the arm at the elbow bring it alongside your body. As your hand goes past your waist, start straightening it out and keep pushing your hand past your bottom. Finish the stroke with the right arm brought forward with the elbow out and up, and your hand just above the water.

When the right arm is extended out the left one should be all the way back and vice versa.

The flutter kick:

Bend your knees slightly and kick your legs up and down in an alternate order.

Your leg kick should seem natural not forced.

Speed

To improve your speed, maximize the time spent on the side. This will enable the shoulders to break the water-line and make bow waves, which will further reduce the impact of water drag on you.