Understanding aperture and depth of field...

It took me a while to work out what aperture was and how it affected the 'depth of field' in my photos, but I finally got it, and I'll share it with you now!  Rather than calling it 'aperture', I call it 'the F number', very technical!  Here are two photos I took from the same distance of the same subject, with different apertures...

 The photo above had a 'low F number' (so F2.8), and the photo above had a 'high F number'.

You can see that the higher the F number, the more in focus the rest of the picture is.  So if you were taking a picture of someone in an interesting setting and you wanted the scenery to feature in the photo, you would want your F number to be higher than if you were taking a photo where the main subject was that person and you weren't bothered about the details of the surroundings. 

Simple!