Database sharding vs partitioning

I have been reading about scalable architectures recently. In that context, two words that keep on showing up with regards to databases are *sharding* and *partitioning*. I looked up descriptions but still ended up confused. Could the experts at stackoverflow help me get the basics right? * What is the difference between *sharding* and *partitioning* ? * Is it true that *'all sharded databases are essentially partitioned (over different nodes), but all partitioned databases are not necessarily sharded'* ?