Short answer
Islam allows spouses considerable freedom in lawful intimacy, but certain acts and circumstances have specific restrictions.
Islamic Guidance
What Islam teaches
The Qur'an permits marital intimacy while explicitly prohibiting intercourse during menstruation and providing guidance regarding the permissible manner of intercourse. Prophetic teachings provide additional boundaries.
Practical Guidance
What you can consider
Couples should learn the relevant rulings from reliable sources and avoid assuming that every practice is permissible simply because it occurs within marriage.
Sources
Qur'an 2:222-223.