Eldest only had one word between 18 months and 22 months. By 2 he could use some short sentences. By 2.5 he was considered above average in speech.
Youngest seemed to be developing speech quite well up until 2, then severely slowed down. He has many, many words and can sight read singular words. He cannot communicate though, no 'can I have a drink', 'I don't like it', 'I want to watch Bing' or anything that is not repetitive from a TV show he likes. He's a month off 3 now.
Both my children are not 'typical' though. Eldest is already on a pathway for possible autism (his speech wasn't the key issue here) and looks like the youngest will get a referral at some point for speech therapy if things don't improve. However, it could all still change in a matter of weeks.
Most children have a 'language explosion' between 2-3, so generally it's nothing to worry about if a 2 year old isn't talking much.