Softwood cuttings = stem cuttings taken of new soft growth during the main growing season (spring and early summer in the UK).
This type of cutting is the fastest to root but requires careful humidity control otherwise it will wilt and die before it produces roots. It is also more susceptible to pest and disease attack than hardwood or semi-ripe cuttings.
Softwood cuttings (YouTube, 3:48)
Have a go at making some softwood cuttings as instructed in the video. If it is not the right time of year for outdoor plants, then you can have a go with house plants.