doc/tutorial/basics: add basics tutorial
Change-Id: I350244d6db5e20be4ab3913dc864f61923b2738f
diff --git a/doc/tutorial/basics/ranges.md b/doc/tutorial/basics/ranges.md
new file mode 100644
index 0000000..7817d04
--- /dev/null
+++ b/doc/tutorial/basics/ranges.md
@@ -0,0 +1,40 @@
+[TOC](Readme.md) [Prev](numbers.md) [Next](rangedef.md)
+
+# Ranges
+
+Ranges define an inclusive range of valid values.
+They work on numbers, strings, and bytes.
+
+The type of a range is the unification of the types of the start and end
+value.
+
+Unifying two ranges results in the overlapping range or an error if there
+is no overlap.
+
+<!-- CUE editor -->
+```
+rn: 3..5 // type int | float
+ri: 3..5 & int // type int
+rf: 3..5.0 // type float
+rs: "a".."mo"
+
+{
+ a: rn & 3.5
+ b: ri & 3.5
+ c: rf & 3
+ d: "ma"
+ e: "mu"
+
+ r1: 0..7 & 3..10
+}
+```
+
+<!-- result -->
+```
+a: 3.5
+b: _|_
+c: 3
+d: "ma"
+e: _|_
+r1: 3..7
+```
\ No newline at end of file
