If you have a machine you can spare, please run a full node. The more nodes there are, the stronger the network is. Also, if you run a full node you can potentially mine your node for information of various kinds. You can tell if you have a full node by giving the following command:
bitcoin-cli getinfo
If the "connections" field is greater than 8, then you are running a full node, congratulations!
You can find information on how to run a full node on bitcoin.org here:
https://bitcoin.org/en/full-nodeTitle of this post should really be "Please run a full node, because..." followed by some short blurb about why that's important. There are various people reading here new or new-ish to bitcoin or are returning to it very interested after hiatus.
Also a reference to bitcoin.org/en/full-node isn't the best. I think they need to shorten that instructional. And what many people don't realize if they have never run a full node before is the port 8333 thing is actually important. That is buried in the text of the instructions at bitcoin.org/en/full-node way at the end, easy to miss, and it's not explained why it's important.
Here are a few examples of reddit discussions lately about full nodes and how-to's
https://www.reddit.com/r/Bitcoin/comments/5yubg0/run_a_014_fullnode_on_raspberrypi3_prunedless/https://www.reddit.com/r/Bitcoin/comments/624xd0/first_time_running_bitcoin_core_full_node/By the way, this handy site tells you kind of why it's important regarding the port issue, and even tells you if port 8333 is open or closed for you.
https://www.lurkmore.com/mining/port8333/