A dress code (/dres kəʊd/) is a set of expectations, either formally or informally defined, regarding appearance, particularly clothing but also including personal grooming such as hairstyles.
If a teacher works for a school or an institute dress codes can range from "wear whatever you like" to requiring to wear a 2 or 3 piece suit to visit high end business students.
In some countries personal tailoring is readily available. In which case bold colours and patterns can be a great way of standing out.
Dressing modestly is always a good idea but especially if you're teaching certain demographics who lack self-control and might be distracted by body parts.
Note if you're a manager, and your company specifies dress codes for your staff, those staff will notice if you don't follow it yourself.
And don't forget to dress up for a job interview.
Teflpedia doesn't have a dress code - you can edit while wearing anything you like.