For those learning English, be aware of spelling differences between regions. Examples -ize vs -ise American: realize, organize, socialize British: realise, organise, socialise -or vs -our American: color, harbor, favor British: colour, harbour, favour -er vs -re American: center, theater, liter British: centre, theatre, litre -ense vs -ence American: defense, license, offense British: defence, licence, offence Other examples: American: check, program, pajamas British: cheque, programme, pyjamas