Consonant, confusing definition

[Starstreams]

Hi
Sorry to ask such an elementary question but I don’t think I really understand what a consonant is?
I’ve referred to these two links but I still don’t understand what they are saying?
Consonant - Wikipedia, the free encyclopedia
What is a Consonant?
like for example this lesson I’m doing says, “Words ending in a consonant..ect”
Free Spelling Course
What dose "words ending in a consonant" mean?
Advanced Thanks

[Starstreams]

Edit
I think I got it now.
They are words unlike vowels for which the air is stopped.
A vowel on the other hand can be a word where the air is not stopped by your lips or tongue.

Example
(Quote from .wisegeek.com)
What is a Vowel?
are sounds for which there are one or more points where air is stopped. In nearly all languages, words must contain at least one vowel. While a word can be formed without any consonants – such as the English words I or way – no word may consist of only consonants, without a vowel.

[Tdol]

You're right- when you say consonants like 'p', you stop the air with your lips and when you say 'd' you stop the air with your tongue.