diff --git a/src/calanonsync/caldav.go b/src/calanonsync/caldav.go
index 76d237c..05a835a 100644
--- a/src/calanonsync/caldav.go
+++ b/src/calanonsync/caldav.go
@@ -28,6 +28,7 @@ type ICal struct {
 	eventData []string // sub slice
 }
 
+// Retrieve the summary (aka title) of the event.
 func (i ICal) Summary() string {
 	for _, s := range i.eventData {
 		if strings.HasPrefix(s, "SUMMARY:") {
@@ -37,6 +38,7 @@ func (i ICal) Summary() string {
 	return ""
 }
 
+// Retrieve the UID of the event.
 func (i ICal) UID() string {
 	for _, s := range i.eventData {
 		if strings.HasPrefix(s, "UID:") {
@@ -46,6 +48,10 @@ func (i ICal) UID() string {
 	return ""
 }
 
+// Internal helper function to retrieve a time from the given field within
+// the event data of the ICal structure. Timezone information are ignored.
+// The time is therefore either a local time or a UTC time, depending on
+// the notation.
 func (i ICal) getTimeField(f string) time.Time {
 	for _, s := range i.eventData {
 		if strings.HasPrefix(s, f) {
@@ -67,10 +73,12 @@ func (i ICal) getTimeField(f string) time.Time {
 	return time.Time{}
 }
 
+// Retrieve the start time of the event.
 func (i ICal) Start() time.Time {
 	return i.getTimeField("DTSTART")
 }
 
+// Retrieve the end time of the event.
 func (i ICal) End() time.Time {
 	return i.getTimeField("DTEND")
 }
@@ -90,6 +98,7 @@ func (i *ICal) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	return nil
 }
 
+// Builds a string representation of the ICal (as ICS).
 func (i ICal) String() string {
 	sb := &strings.Builder{}
 	for n, line := range i.data {
@@ -101,6 +110,8 @@ func (i ICal) String() string {
 	return sb.String()
 }
 
+// Parses the given ICal into structure. It identifies the first (and only
+// the first) event within the given calendar.
 func ParseICal(r io.Reader) (*ICal, error) {
 	var data []string
 	scanner := bufio.NewScanner(r)
@@ -136,6 +147,9 @@ func ParseICal(r io.Reader) (*ICal, error) {
 	}, err
 }
 
+// Create a new empty ICal structure with the given parameters.
+// Currently only supports time based events; date-only is not
+// supported.
 func CreateICal(uid, summary string, start, end time.Time) *ICal {
 	model := struct {
 		UID     string
@@ -177,6 +191,12 @@ type CalDAVItem struct {
 	*ICal
 }
 
+// Retrieve all events from the configured CalDAV server.
+// Each item will contain the original URL in relative format
+// as well as the ICal data for the given event.
+//
+// It is expected that each event is a ICal calendar with only
+// a single event.
 func (c *CalDAV) GetEvents() ([]CalDAVItem, error) {
 	req, err := http.NewRequest("PROPFIND", c.URL, strings.NewReader(`<propfind xmlns='DAV:'><prop><calendar-data xmlns='urn:ietf:params:xml:ns:caldav'/></prop></propfind>`))
 	if err != nil {
@@ -207,6 +227,10 @@ func (c *CalDAV) GetEvents() ([]CalDAVItem, error) {
 	return result, nil
 }
 
+// Put the given item on the configured CalDAV server, either updating
+// an existing item or creating a new one.
+// The target URL is calculated by the URL in the settings together with
+// the HRef of the CalDAV item.
 func (c CalDAV) UploadItem(item CalDAVItem) error {
 	itemURL, _ := url.Parse(item.HRef)
 	base, _ := url.Parse(c.URL)
@@ -231,6 +255,9 @@ func (c CalDAV) UploadItem(item CalDAVItem) error {
 	return nil
 }
 
+// Removes the given item from the configured CalDAV server using the
+// calculated URL from the settings together with the HRef of the given
+// CalDAV item.
 func (c CalDAV) DeleteItem(item CalDAVItem) error {
 	itemURL, _ := url.Parse(item.HRef)
 	base, _ := url.Parse(c.URL)
diff --git a/src/calanonsync/ews.go b/src/calanonsync/ews.go
index b67c113..74f4941 100644
--- a/src/calanonsync/ews.go
+++ b/src/calanonsync/ews.go
@@ -29,6 +29,10 @@ type CalendarItem struct {
 	CalendarItemType string
 }
 
+// Build a hash for the given calendar item by combining the UID and
+// the recurrenceId therefore guaranteeing a unique identifier for the
+// event, even if it has been a calculated recurrence (which would
+// otherwise share the same UID).
 func (ci CalendarItem) Hash() string {
 	h := md5.New()
 	h.Write([]byte(ci.UID))
@@ -59,6 +63,9 @@ func NewEWSCalendar(url, username, password string) *EWSCalendar {
 	}
 }
 
+// Internal helper to prepare a request to the EWS server. This is a shortcut
+// since all requests share some similarities: they transmit XML and receive
+// XML. Also it needs a basic auth header.
 func (e *EWSCalendar) prepareRequest(body io.Reader) (req *http.Request, err error) {
 	req, err = http.NewRequest(http.MethodPost, e.url, body)
 	req.Header.Set("Content-Type", "text/xml")
@@ -67,6 +74,8 @@ func (e *EWSCalendar) prepareRequest(body io.Reader) (req *http.Request, err err
 	return
 }
 
+// Request the ID of the default calendar folder. This is necessary to do
+// the actual event query.
 func (e *EWSCalendar) getCalendarFolderID() (id *FolderId, err error) {
 	req, err := e.prepareRequest(strings.NewReader(folderIdRequest))
 	if err != nil {
@@ -108,6 +117,7 @@ func (e *EWSCalendar) getCalendarFolderID() (id *FolderId, err error) {
 	}
 }
 
+// Query events from the given folder in the given timeframe.
 func (e *EWSCalendar) getCalendarItems(folder *FolderId, start, end time.Time) (items []CalendarItem, err error) {
 	b := &bytes.Buffer{}
 	model := struct {