Morihei Ueshiba (O'Sensei), Aikido is a purely defensive martial art, involving no kicking or punching per se. Instead a skilled aikidoka redirects an opponents energy (or ki) to throw or immobilise them. All techniques are learned with a partner in a noncompetitive environment. In the Figure nage (the thrower) performs munetsuki kotegaeshi - a wrist turn on a punch. In this case nage holds on, sending uke (the attacker) into break-fall. Taninzugake (freestyle) training with several partners is often practiced as well. Bokken (wooden sword) and jo (staff) are often used as training aids to help understand the principles of Aikido. Aikido is often called the art of peace, because conflict is neutralised without the need for force. Breathing methods and other forms of meditation are sometimes also practiced.
Sometimes brutal, sometimes soft - depending on the practitioners' view of the art and its philosophy. Below Joe Thambu Sensei demonstrates the Yoshinkan kihon from static to high-level practice. I have had the good fortune to train with Thambu Sensei a few times, a generous teacher and very accommodating to those from outside his school.
Stefan Stenudd in action showing the subtlety in kuzushi (balance breaking) that makes Aikido so effective and almost magical at a high level.
Aikido when done softly with martial understanding can be very dynamic. See here the late Iwao Tamura Sensei in action. I was fortunate to attend several seminars by him and take ukemi on a number of occasions.
O'Sensei was famous for the use of ki power, as seen in this demonstration. Not the comments on the clip (go to full screen Youtube to see). I have had some feedback from one of the uke's.