Kumite

Beginners are usually introduced to kumite training with 'gohon kumite' (five-step sparring). In many dojos, students are instead started with 'sanbon kumite' (three-step sparring). Two karateka are required for the exercise. Once they pair up and bow, the attacking karateka steps back into a zenkutsu dachi (front stance) while executing a gedan barai (low block) and announces in a clear, audible fashion the attack. The first type is designated 'jodan' (high level), where they will subsequently execute a high oi-zuki. Their partner must then react by stepping back and executing an age-uke to block the attack. This is repeated until the fifth oi-zuki, when the defender executes a minor counter in the form of a gyaku zuki. The defender is expected to kiai with their counter attack.
That completes one sequence. The next step is for the karateka to return to yoi position (in some associations the counter-attacker moves forward to the yoi position, in some backwards) and the one that was defending takes a turn at attacking, repeating the sequence above.
The other type of gohon kumite is designated 'chudan' (mid level). The differences are that chudan level oi-zuki are used by the attacker and soto-uke blocks are used by the defender.
The next stage of kumite training is the 'sanbon kumite' (three-step sparring). As its name suggest it involves three steps. It is homologous to gohon kumite but instead of five steps, has three.
At intermediate level (usually above 5th kyu), karateka are expected to learn 'ippon kumite' (one step sparring). Though it is only one step, it is more advanced because it involves a greater variety of attacks and blocks. It also requires the defender to execute a minor counter in a timely fashion. Minor counters can be almost anything, including strikes, grapples and take-downs.
The next level of kumite is the 'jiyu ippon kumite' (freestyle one step sparring)(Tsutomu Ohshima actually says in his book "Notes on Training" that jiyu ippon kumite is the most realistic practice in Shotokan Karate, and that it is more realistic than jiyu kumite). This is almost the same as ippon kumite but requires the karateka to be in motion. Practice in this is beneficial in improving jiyu kumite (freestyle sparring) skills, and also provides an opportunity for practicing major counters (as opposed to minor counters).
Usually the last element of sparring to be introduced is jiyu kumite (free sparring) where two participants are free to use any choice of karate technique or combination attacks and the opponent is free to avoid, block and attack at will. Tradition in shotokan karate is that jiyu kumite uses controlled contact to the opponent. Participants are encouraged to make contact with their opponent but to withdraw their attack after surface contact has been made. This allows a full range of target areas to be attacked (including punches and kicks to the face, head, throat and body) with no padding or protective gloves but maintains a healthy degree of safety for the participants. The use of throws and takedowns is permitted in free sparring, however it is very unusual for fights to involve extended grappling or ground-wrestling as shotokan practitioners are encouraged to finish a downed opponent with a punch or kick.
An additional method of training which is usually introduced for higher grades is kaishu ippon kumite. This starts in a similar manner to jiyu ippon kumite; one karateka names the attack they intend to throw, attacks, and their partner blocks and counters their attack. Unlike jiyu ippon kumite, however, the original attacker must block their partner's counter-attack and strike back at them. This exercise is often considered more difficult than either jiyu ippon kumite or free sparring as participants cannot escape to a safe distance.