It's time to trill out. In music a trill is defined as a rapid alternation of two notes either a tone or semi-tone apart. Now that we've got the dictionary definition established it's much easier to learn a trill by actually doing it. Trills can be played on any melodic instrument - vibraphone, flute, cello, etc. And, of course, instruments like guitar and piano.
The animated diagram below shows a trill using a C note and E note. The trill also jumps between two octaves.
It's probably logical to assume that this trill is in a C Major. However, without any musical context or the addition of a third note it cannot be stated clearly whether this trill is major or minor. The bonus here is that you could use this trill in any song in the key of C whether it's Major or minor progression.
Not only that, it would work pretty cool in a song that's in the key of a minor. This post won't explore the theory about that here. Here's what you can take out of this. If you're fiddling around with lead type playing and want something new to add in the keys of C Major, c minor or a minor why not throw in one of these trills.
The speed shown in this animated diagram is a moderate speed to help ensure you can swap between the octave jumps on time. Trills are usually played faster. Adjust to suit and happy jamming.