I’ve seen lots of conversations on photography forums about how to get the blurry background (and fun arguments about the use of the word bokeh, which is a really fun word to say. I like to use it, a lot. Because its fun.)

These are the three ways in which you can achieve a blurry background:

F-Stop/Apature – wider like 2.0 and lower makes for very pretty effects
Smaller margin of error means more difficult to nail focus if you have not practiced a lot.

Auto users: Pop your camera into apature priority mode, which is about the same as auto accept you can control the f-stop/apapture and set it to its LOWEST which on an entry level DSLR and kit lens may be 3.0 – 4.5 (try zooming all the way out, and all the way in to see which zoom gets you the lowest setting, those lens’s lowest setting actually varies based on your zoom length at any given moment. Did that make sense? If not please comment!). You can still do this without being in manual!

Focal Length – 85mm + makes for pretty portraits
More dummy proof and unique looking but costs $$$ to get an 85mm lens (if you have a kit zoom lens zoom all the way IN then step back as needed and zoom with your FEET, keeping the camera zoomed all the way in, these tricks are funny aren’t they??)

Distance – having your subject far away from the background, and stand close to your subject!
Best practice, rule of thumb – aka always do this unless you want them leaning against something

50mm set to 2.0, background very far away, me pretty close to the kid considering its 50mm on FF. (What did you jyst say brandy?? FF = Full Frame camera, so 50mm on full frame is more like what you would get if you used a 35mm on a consumer grade DSLR, it means I want you to understand 50mm on my camera may not be the same as 50mm on yours.)

50mm at 1.4, again I am pretty close to the niblet and the background  is 20+ feet away.

50mm at 1.4, I am at such a shallow depth of field (aka 1.4) it does not matter that the ground is only 3 feet away.

You can get pretty blurred/bokeh backgrounds with a zoom lens as others stated, like 100mm will give you some srsly pretty blurred background that is actually very different in quality then the above. When working at 85mm + you can get some really interesting and unique quality photos in particular if you combine the 85mm with a shallow depth of field like 2.0, as a general rule though I would say do not work below 2.0 until all your 2.0 shots are in focus. You CAN get a lens that goes down that low for cheap, the “niffty fiffty” 50mm 1.8 or the 35mm 1.8, everyone recommends this to people who get a DSLR and with good reason, but stay above 2.0 until your getting sharp shots, then venture below!