Cardigans are open front knitwear, typically with buttons, that resemble something between a sweater and a jacket. These were traditionally wool garments, but modern cardigans are made from all ranges of fibre.
The cardigan was named after the 7th Earl of Cardigan, James Brudenell - a British officer who led the infamous Charge of the Light Brigade, and whose iconic uniform often featured a button-up jacket. The garment was then popularized by Coco Chanel, who stated that she preferred the open front nature of the cardigan because she didn't have to pull it over her head and thus ruin her hair.
Generally thought of as a fashion accessory from the 20s or 30s, cardigan popularity has seen a resurgence in ther 2010s as part of the business-casual trend among young professionals. If you enjoy knitting open front tops that are a little bit sweater and a little bit jacket, the career seekers in your life are likely going to be more than happy to receive a bespoke cardigan as a gift.