Parenthesis

The normal progression of a sentence is interrupted by extra information or explanations enclosed in commas, brackets or dashes. The extra information can be a single word, a phrase or even a sentence.

Examples:

• We (myself, wife Jessie and daughters Wanda and Jennifer) boarded our boat 'Queen', a Duchess class vessel barely a year old, at Black Prince Holidays' Chirk boatyard.
• The boats have remarkably few controls and we were given a thorough briefing about 'driving' ours–along with advice on mooring, lock operation and safety considerations–by Kate, who even set off with us for a few minutes to ensure we were confident.