diff --git a/qlog/event.go b/qlog/event.go
new file mode 100644
index 00000000..9d49f87d
--- /dev/null
+++ b/qlog/event.go
@@ -0,0 +1,41 @@
+package qlog
+
+import (
+	"time"
+
+	"github.com/francoispqt/gojay"
+)
+
+var eventFields = [4]string{"time", "category", "event", "data"}
+
+type events []event
+
+var _ gojay.MarshalerJSONArray = events{}
+
+func (e events) IsNil() bool { return e == nil }
+func (e events) MarshalJSONArray(enc *gojay.Encoder) {
+	for _, ev := range e {
+		enc.Array(ev)
+	}
+}
+
+type eventDetails interface {
+	Category() category
+	Name() string
+	gojay.MarshalerJSONObject
+}
+
+type event struct {
+	Time time.Time
+	eventDetails
+}
+
+var _ gojay.MarshalerJSONArray = event{}
+
+func (e event) IsNil() bool { return false }
+func (e event) MarshalJSONArray(enc *gojay.Encoder) {
+	enc.Float64(float64(e.Time.UnixNano()) / 1e6)
+	enc.String(e.Category().String())
+	enc.String(e.Name())
+	enc.Object(e.eventDetails)
+}
diff --git a/qlog/event_test.go b/qlog/event_test.go
new file mode 100644
index 00000000..5112f213
--- /dev/null
+++ b/qlog/event_test.go
@@ -0,0 +1,54 @@
+package qlog
+
+import (
+	"bytes"
+	"encoding/json"
+	"time"
+
+	"github.com/francoispqt/gojay"
+
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+type mevent struct{}
+
+var _ eventDetails = mevent{}
+
+func (mevent) Category() category                   { return categoryConnectivity }
+func (mevent) Name() string                         { return "mevent" }
+func (mevent) IsNil() bool                          { return false }
+func (mevent) MarshalJSONObject(enc *gojay.Encoder) { enc.StringKey("event", "details") }
+
+var _ = Describe("Events", func() {
+	It("marshals the fields before the event details", func() {
+		now := time.Now()
+
+		buf := &bytes.Buffer{}
+		enc := gojay.NewEncoder(buf)
+		Expect(enc.Encode(event{
+			Time:         now,
+			eventDetails: mevent{},
+		})).To(Succeed())
+
+		var decoded []interface{}
+		Expect(json.Unmarshal(buf.Bytes(), &decoded)).To(Succeed())
+		Expect(decoded).To(HaveLen(4))
+
+		// 1st field
+		Expect(eventFields[0]).To(Equal("time"))
+		Expect(time.Unix(0, int64(1e6*decoded[0].(float64)))).To(BeTemporally("~", now, 2*time.Microsecond))
+
+		// 2nd field
+		Expect(eventFields[1]).To(Equal("category"))
+		Expect(decoded[1].(string)).To(Equal(categoryConnectivity.String()))
+
+		// 3rd field
+		Expect(eventFields[2]).To(Equal("event"))
+		Expect(decoded[2].(string)).To(Equal("mevent"))
+
+		// 4th field
+		Expect(eventFields[3]).To(Equal("data"))
+		Expect(decoded[3].(map[string]interface{})["event"]).To(Equal("details"))
+	})
+})
diff --git a/qlog/types.go b/qlog/types.go
index 02154ad7..de24581c 100644
--- a/qlog/types.go
+++ b/qlog/types.go
@@ -35,3 +35,28 @@ type connectionID protocol.ConnectionID
 func (c connectionID) String() string {
 	return fmt.Sprintf("%x", []byte(c))
 }
+
+// category is the qlog event category.
+type category uint8
+
+const (
+	categoryConnectivity category = iota
+	categoryTransport
+	categorySecurity
+	categoryRecovery
+)
+
+func (c category) String() string {
+	switch c {
+	case categoryConnectivity:
+		return "connectivity"
+	case categoryTransport:
+		return "transport"
+	case categorySecurity:
+		return "security"
+	case categoryRecovery:
+		return "recovery"
+	default:
+		panic("unknown category")
+	}
+}
diff --git a/qlog/types_test.go b/qlog/types_test.go
new file mode 100644
index 00000000..c2f2e68b
--- /dev/null
+++ b/qlog/types_test.go
@@ -0,0 +1,15 @@
+package qlog
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Types", func() {
+	It("has a string representation for the category", func() {
+		Expect(categoryConnectivity.String()).To(Equal("connectivity"))
+		Expect(categoryTransport.String()).To(Equal("transport"))
+		Expect(categoryRecovery.String()).To(Equal("recovery"))
+		Expect(categorySecurity.String()).To(Equal("security"))
+	})
+})